579 Sentences With "cochlea" | Random Sentence Generator

TEMPORAL LOBE Cochlea Eardrum TEMPORAL LOBE Cochlea Eardrum TEMPORAL LOBE Cochlea Eardrum By The New York Times | Sources: Allan H. Frey; Centers for Disease Control and Prevention The false sensations, the experts say, may account for a defining symptom of the diplomatic incidents — the perception of loud noises, including ringing, buzzing and grinding.

The technology utilizes cells derived from the cochlea of mice.

It also worked in a mouse cochlea removed from the body.

"The energy travels into your inner ear and the cochlea," Metzger tweeted.

These cells lie within a spiral organ in the inner ear known as the cochlea.

Our own ears have what's called a cochlea inside them, a sort of long sealed canal filled with liquid and motion-sensitive cells; when sound hits the end of the cochlea, different parts of it vibrate depending on the frequencies that make up the sound.

Inner ear tinnitus may be caused by injuries to the cochlea due to loud noise or inflammation.

He says hearing aids won't work, because the injectable agents destroy the inner workings of the cochlea.

You can hear high-pitch noises because they trigger hairs near the outer part of the cochlea.

"The hair cells — the sensory cells — in the cochlea almost never come back [if they die]," he added.

Tim was completely or partly deaf from the age of 18 until a cochlea implant restored some hearing.

Tinnitus is more common in people with hearing loss, caused by damage to the cochlea or the auditory nerve.

We can do the same work of the cochlea, but transmit the resulting frequency information, instead, via your skin.

Dugan compared the technology to the cochlea in your ear, which translates sound into information readable by your brain.

They in turn tap the cochlea, a snail shell–looking structure that contains thousands of delicate hairs and fluid.

Another part of the inner ear, a thin, bony structure within the cochlea, provided further evidence of the ability.

The implant replaces the tiny hairs in the cochlea that were destroyed by the toxic medicine with electronic signals.

Powered by grief and an elaborate soundscape, it is a heartbreaker of a rock opera shot straight to your cochlea.

Inside the cochlea there are over 16,000 hairlike cells, which take vibrations entering your ear and convert them into nerve impulses.

As hearing declines with age, the cochlea, the part of the inner ear that receives and transmits sound, sustains irreversible damage.

But his lab has focused on the hair cells inside the cochlea and the neurons from the auditory nerve connected to it.

Studies show that auditory signals are transmitted from the cochlea, in the inner ear, to a brain structure called the dorsal cochlear nucleus.

I'm not saying the MA770 lacks capability for cochlea-rupturing bass the younger generation (including myself) seems to have an unhealthy obsession with.

Sensorineural hearing loss occurs after damage to the inner ear, called the cochlea, or the nerve pathways from the inner ear to the brain.

The cochlea converts mechanical signals into electrical ones, which it then passes to the auditory nerve, which transmits it to the brain for processing.

This tiny signal originates in the cochlea and vibrates the ear drum, turning it into a speaker and playing sound back out of your ear.

YAO MING and COCHLEA came to mind pretty easily, and then AGELESS, and some of the automotive clues like ETHANOL and the clever REAR-END.

The third mouse had the same mutation, but had been given a functioning version of the faulty gene, delivered to its cochlea by a harmless virus.

Facebook says its technology will act like the cochlea part of the ear, which translates sound into frequencies that are sent to the brain and decoded.

But whether it's the sound of chickens or my beautiful voice, it all enters your ear through the cochlea, a shell-like structure in the inner ear.

It's been building prototypes of hardware and software that let your skin mimic the cochlea in your ear that translates sound into specific frequencies for your brain.

The mic is waterproof and its speaker works using bone conduction, meaning it uses vibrations to transmit sounds to the cochlea through the bones in the user's skull.

These vibrations cause the fluid inside your cochlea (inner ear) to move and this in turn activates your hair cells, which then sends the signal to your auditory nerve.

The bit passes just half a millimeter from the facial nerve, and another half a millimeter from the taste nerve, before entering the spiraling cochlea of the inner ear.

The team have adapted an otoacoustic emissions test, which measures the sounds created by the inner ear when the cochlea responds to sound, and put it inside the headphones.

These are called "otoacoustic emissions," and they happen when the specialized hairs on and inside the cochlea — called hair cells — vibrate either spontaneously or in response to auditory stimulation.

Noticing that the cells of the inner ear (the cochlea) express some of the same surface proteins, the team began exploring whether a similar approach could work in the ear.

There's an inherent masochism to it—massive kick drums shatter sternums and cochlea with the force of a pneumatic hammer at speeds that often top out at over 200 BPM.

These individuals sometimes use special devices called bone anchored hearing aids, which transmit sound through bone vibration directly through the cochlea (the inner ear), rather than through the outer and middle ears.

Jonas Oppenheimer, a technician in the lab of David Reich, a geneticist at Harvard, sandblasts an ancient skull fragment to find the cochlea, or inner ear, the area likeliest to retain DNA.

Noise-induced damage to the nearly 15,000 tiny hair cells and neurons in the cochlea or to the auditory nerve is by far the leading cause of what's known as sensorineural hearing loss.

Exercise may protect against hearing loss by improving blood flow to the cochlea, the snail-shaped structure in the inner ear that converts sound waves into nerve signals that are sent to the brain.

The researchers are still figuring out exactly when this kind of therapy would be the most effective (it would likely be at a very young age, as the cochlea degenerates over time in people with hereditary hearing loss).

The science behind the app is simple: sound causes the hair cells in the cochlea (the spiral-shaped cavity in the inner ear) to vibrate and send nerve signals to the brain, but the hair cells lose sensitivity over time.

It enters the auricle—the crumpled cone of the ear—and echoes through the auditory canal, strikes the eardrum, chimes the bones of the middle ear, and goes spinning down the sousaphone of the cochlea, tripping nerves inside like keys on a piano.

When she was twenty, she received a cochlear implant—a surgically placed electronic device that transmits sound impulses from a microphone near the ear to electrodes in the cochlea, bypassing the eardrum and directly stimulating the hair cells and the auditory nerve fibres.

In this case, researchers from the University of Bern have been working on a robot that performs the most delicate and potentially damaging step: drilling into the skull at the precise location and depth to give access to the right part of the cochlea.

The people in the video are tapping the spot on the skull exactly where these bone anchored hearing aids go, which made Polley suppose that the tapping is generating sound vibrations to the cochlea that mask the tinnitus in the same way other maskers function.

At the other end of the canal, roughly an inch inside your head, those waves strike the tympanic membrane, also known as the eardrum, and the resulting vibrations pass through three small bones and into the cochlea, a fluid-filled organ shaped like a snail.

The drug, which had been developed for treating Alzheimer's but turned out to be unsuitable for that, suppresses the activity of a protein that prevents hair cells from being created by so-called supporting cells—cells in the cochlea that function something like stem cells.

All the decisions involving the raising of a deaf kid in the 21st century really came down to one: Do his father and I ask surgeons to drill into my son's head and thread an electrode array into his cochlea, all for the sake of sound?

There are existing drugs for effectively treating middle-ear infections, "but nothing that works on the cochlea," said Paula Cobb, executive vice president of corporate development at Decibel Therapeutics, a Boston-based start-up launched in 2015 with $52 million in venture capital from biotech investment firm Third Rock Ventures and SR One, the VC arm of pharma giant GlaxoSmithKline.

The cochlear cupula is a structure in the cochlea. It is the apex of the cochlea. The bony canal of the cochlea takes two and three-quarter turns around the modiolus. The modiolus is about 30 mm.

The active mechanism is dependent on the cochlea being in good physiological condition. However, the cochlea is very susceptible to damage.

3D model of cochlea and semicircular canals The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea. The name cochlea derives .

The human ear is made up of three areas: the outer, middle and inner ear. Within the inner ear sits the cochlea. The cochlea is a snail-shaped formation that enables sound transmission via a sensorineural route, rather than through a conductive pathway. The cochlea is a complex structure, consisting of three layers of fluid.

The modiolus is a conical shaped central axis in the cochlea. The modiolus consists of spongy bone and the cochlea turns approximately 2.75 times around the central axis in humans.Thieme Atlas of Anatomy The cochlear nerve, as well as spiral ganglion is situated inside it. The cochlear nerve conducts impulses from the receptors located within the cochlea.

In this way, completely deaf patients can perceive sounds again. However, As soon as there are problems not only at the level of the cochlea, but also in the middle ear (the so-called conductive losses), then there are more efficient ways to get sound to the partially functioning cochlea. The most obvious solution is a BAHA, which brings the sound to the cochlea via bone conduction. However, patients who have both problems with the cochlea, as with the middle ear (i.e.

The size of cochlea has been measured throughout its evolution based on the fossil record. In one study, the basal turn of the cochlea was measured, and it was hypothesized that cochlear size correlates with body mass. The size of the basal turn of the cochlea was not different in Neanderthals and Holocene humans, however it became larger in early modern humans and Upper Paleolithic humans. Furthermore, the position and orientation of the cochlea is similar between Neanderthals and Holocene humans, relative to plane of the lateral canal, whereas early modern and upper Paleolithic humans have a more superiorly placed cochlea than Holocene humans.

The drug is understood to damage multiple regions of the cochlea, causing the death of outer hair cells, as well as damage to the spiral ganglion neurons and cells of the stria vascularis. Long-term retention of cisplatin in the cochlea may contribute to the drug's cochleotoxic potential. Once inside the cochlea, cisplatin has been proposed to cause cellular toxicity through a number of different mechanisms, including through the production of reactive oxygen species. The decreased incidence of oxaliplatin ototoxicity has been attributed to decreased uptake of the drug by cells of the cochlea.

He made some of his dogs temporarily blind, by sewing their eyelids together and reported, that the accuracy of discrimination was not affected. He also destroyed one cochlea in some other "well-trained dogs", and also reported no disturbance. When the other cochlea was destroyed, all discrimination ceased. Dogs subjected to extirpation of both cochlea before any training was attempted did not learn to discriminate at all.

Birds have an auditory system similar to that of mammals, including a cochlea. Reptiles, amphibians, and fish do not have cochleas but hear with simpler auditory organs or vestibular organs, which generally detect lower- frequency sounds than the cochlea. The cochlea of birds is similar to that of crocodiles, consisting of a short, slightly curved bony tube within which lies the basilar membrane with its sensory structures.

He has used it to create novel quantum-inspired architectures that do spectrum analysis like the biological inner ear or cochlea, i.e. a 'Quantum Cochlea'. Professor Sarpeshkar's book introduced a novel form of electronics termed Cytomorphic electronics, i.e., electronics inspired by cell biology .

When the recruitment is associated with cochlea then the concept is known as Partial Recruitment.

The inner ear is composed of bony canals (bony labyrinth). It is divided into three parts: vestibule, semicircular canals and the cochlea. These vestibule and the semicircular parts play a key role in the sensors for balancing. The cochlea plays an important part in hearing.

Turritella cochlea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.

Flowchart of sound passage - inner ear The cochlea of the inner ear, a marvel of physiological engineering, acts as both a frequency analyzer and nonlinear acoustic amplifier. The cochlea has over 32,000 hair cells. Outer hair cells primarily provide amplification of traveling waves that are induced by sound energy, while inner hair cells detect the motion of those waves and excite the (Type I) neurons of the auditory nerve. The basal end of the cochlea, where sounds enter from the middle ear, encodes the higher end of the audible frequency range while the apical end of the cochlea encodes the lower end of the frequency range.

In the mammalian cochlea, wave amplification occurs via the outer hair cells of the organ of Corti. These cells sit directly above a basilar membrane (BM) that has high sensitivity for differences in frequency. Sound waves enter the scala vestibuli of the cochlea and travel throughout it, carrying with them various sound frequencies. These waves exert a pressure on the basilar and tectorial membranes of the cochlea which vibrate in response to sound waves of different frequencies.

Heller has reported success in re-growing cochlea hair cells with the use of embryonic stem cells.

The cochlea and vestibule, viewed from above. The labyrinth can be divided by layer or by region.

LGR5+ve stem cells were pinpointed as the precursor for sensory hair cells that line the cochlea.

The name cochlea is derived from the Latin word for snail shell, which in turn is from the Greek κοχλίας kokhlias ("snail, screw"), from κόχλος kokhlos ("spiral shell")etymology of "cochleㄷa", in reference to its coiled shape; the cochlea is coiled in mammals with the exception of monotremes.

The basilar membrane is widest (0.42–0.65 mm) and least stiff at the apex of the cochlea, and narrowest (0.08–0.16 mm) and stiffest at the base (near the round and oval windows). High-frequency sounds localize near the base of the cochlea, while low-frequency sounds localize near the apex.

The base of the cochlea, closest to the outer ear, is the most stiff and narrow and is where the high-frequency sounds are transduced. The apex, or top, of the cochlea is wider and much more flexible and loose and functions as the transduction site for low-frequency sounds.

GIPC3 is thought to be important for acoustic signal acquisition and propagation in hair cells of the mammalian cochlea.

A cross-section of the cochlea showing the organ of Corti. Cross-section through the spiral organ of Corti at greater magnification. Rosenthal's canal or the spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2¾ turns about the modiolus, the central axis of the cochlea that contains the spiral ganglion. Specialized inner ear cell include: hair cells, pillar cells, Boettcher's cells, Claudius' cells, spiral ganglion neurons, and Deiters' cells (phalangeal cells).

Pioneered by Georg von Békésy, a method to observe the basilar membrane in action came about in the mid 1900s. Békésy isolated the cochlea from human and animal cadavers and labeled the basilar membrane with silver flakes. This allowed strobe imaging to capture the movement of the membrane as sounds stimulated the hair cells. This led to the solidification of the idea that high frequencies excite the basal end of the cochlea and provided new information that low frequencies excite a large area of the cochlea.

Not only does the cochlea "receive" sound, a healthy cochlea generates and amplifies sound when necessary. Where the organism needs a mechanism to hear very faint sounds, the cochlea amplifies by the reverse transduction of the OHCs, converting electrical signals back to mechanical in a positive-feedback configuration. The OHCs have a protein motor called prestin on their outer membranes; it generates additional movement that couples back to the fluid–membrane wave. This "active amplifier" is essential in the ear's ability to amplify weak sounds.

The central axons form synaptic connections with cells in the cochlear nucleus of the brainstem. The cell bodies of the cochlear nerve lie within the cochlea and collectively form the spiral ganglion, named for the spiral shape it shares with the cochlea. These central axons exit the cochlea at its base and form a nerve trunk, which, in humans, is approximately one inch long. This travels in parallel with the vestibular nerves through the internal auditory canal, through which it connects to the brainstem.

This gene affects the potassium channel count and their productivity in several parts of the body. Cochlea crossection Since the main mutation for EAST syndrome is in the KCNJ10 gene, it affects the potassium channels found in the inner ear cells. This includes the stria vascularis region of the inner ear, which is the upper portion of the fluid filled spiral ligament of the cochlea. The cochlea is the main region that translates sound waves into neurological signals to be interpreted by the brain.

An analog ear or analog cochlea is a model of the ear or of the cochlea (in the inner ear) based on an electrical, electronic or mechanical analog. An analog ear is commonly described as an interconnection of electrical elements such as resistors, capacitors, and inductors; sometimes transformers and active amplifiers are included.

He concluded that his observations showed how different sound wave frequencies are locally dispersed before exciting different nerve fibers that lead from the cochlea to the brain. In 1961, he was awarded the Nobel Prize in Physiology or Medicine for his research on the function of the cochlea in the mammalian hearing organ.

The stapes (stirrup) ossicle bone of the middle ear transmits vibrations to the fenestra ovalis (oval window) on the outside of the cochlea, which vibrates the perilymph in the vestibular duct (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in a pressure gain of about 20× from the original sound wave pressure in air. This gain is a form of impedance matching – to match the soundwave travelling through air to that travelling in the fluid–membrane system. At the base of the cochlea, each duct ends in a membranous portal that faces the middle ear cavity: The vestibular duct ends at the oval window, where the footplate of the stapes sits.

The olivocochlear system is a component of the auditory system involved with the descending control of the cochlea. Its nerve fibres, the olivocochlear bundle (OCB), form part of the vestibulocochlear nerve (VIIIth cranial nerve, also known as the auditory-vestibular nerve), and project from the superior olivary complex in the brainstem (pons) to the cochlea.

Cochlea is Latin for “snail, shell or screw” and originates from the Greek word κοχλίας kokhlias. The modern definition, the auditory portion of the inner ear, originated in the late 17th century. Within the mammalian cochlea exists the organ of Corti, which contains hair cells that are responsible for translating the vibrations it receives from surrounding fluid-filled ducts into electrical impulses that are sent to the brain to process sound. This spiral-shaped cochlea is estimated to have originated during the early Cretaceous Period, around 120 million years ago.

The cochlea is the tri-chambered auditory detection portion of the ear, consisting of the scala media, the scala tympani, and the scala vestibuli. Regarding mammals, placental and marsupial cochleae have similar cochlear responses to auditory stimulation as well as DC resting potentials. This leads to the investigation of the relationship between these therian mammals and researching their ancestral species to trace the origin of the cochlea. This spiral-shaped cochlea that is in both marsupial and placental mammals is traced back to approximately 120 million years ago.

The cochlea is tonotopically mapped in a spiral fashion, with lower frequencies localizing at the apex of the cochlea, and high frequencies at the base of the cochlea, near the oval and round windows. With age, comes a loss in distinction of frequencies, especially higher ones. The electrodes of the implant are designed to stimulate the array of nerve fibers that previously responded to different frequencies accurately. It is important to note that due to spatial constraints, the cochlear implant may not be inserted all the way into the cochlear apex.

The picture shows the osseous labyrinth. The modiolus is not labeled; it's at the axis of the spiral of the cochlea.

Hair cells responsible for transduction—changing mechanical changes into electrical stimuli are present in the organ of Corti in the cochlea.

The basilar membrane is a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani. The basilar membrane moves up and down in response to incoming sound waves, which are converted to traveling waves on the basilar membrane.

When there are vibrations in the air, the eardrum is stimulated. The eardrum collects these vibrations and sends them to receptor cells. The ossicles which are connected to the eardrum pass the vibrations to the fluid-filled cochlea. Once the vibrations reach the cochlea, the stirrup (part of the ossicles) puts pressure on the oval window.

The inner ear consists of the cochlea and several non- auditory structures. The cochlea has three fluid-filled sections (i.e. the scala media, scala tympani and scala vestibuli), and supports a fluid wave driven by pressure across the basilar membrane separating two of the sections. Strikingly, one section, called the cochlear duct or scala media, contains endolymph.

The genes for alpha-tectorin and beta-tectorin (this protein) encode the major noncollagenous proteins of the tectorial membrane of the cochlea.

This opening allows the vibrations to move through the liquid in the cochlea where the receptive organ is able to sense it.

Cochlea and vestibular system The semicircular canal system detects rotational movements. The semicircular canals are its main tools to achieve this detection.

In Australia it is reported as being an obligate commensal inside solitary, free-living corals such as Heterocyathus aequicostatus and Heteropsammia cochlea.

When a vibration is carried through the cochlea, the fluid within the three compartments causes the basilar membrane to respond in a wave-like manner. This wave is referred to as a 'travelling wave'; this term means that the basilar membrane does not simply vibrate as one unit from the base towards the apex. When a sound is presented to the human ear, the time taken for the wave to travel through the cochlea is only 5 milliseconds. When low-frequency travelling waves pass through the cochlea, the wave increases in amplitude gradually, then decays almost immediately.

Mondini dysplasia, also known as Mondini malformation and Mondini defect, is an abnormality of the inner ear that is associated with sensorineural hearing loss. This deformity was first described in 1791 by Mondini after examining the inner ear of a deaf boy. The Mondini dysplasia describes a cochlea with incomplete partitioning and a reduced number of turns, an enlarged vestibular aqueduct and a dilated vestibule. A normal cochlea has two and a half turns, a cochlea with Mondini dysplasia has one and a half turns; the basal turns being normally formed with a dilated or cystic apical turn to the cochlear.

The group is also notable for adaptations to the structures of their ear. The structure of their inner-ear is almost avian, with bird-like semicircular canals and an extended cochlea. For birds, an extended cochlea allows them to hear across an increased range of frequencies, suggesting a similar function in the ponderous therizinosaurids and also allowing them a good hearing and balance, which indeed, are traits better associated with carnivorous theropods. Furthermore, the lengthening of the cochlea, an adaptation which has independently evolved in a number of other theropod groups, is thought to further improve auditory acumen.

Frequency resolution occurs on the basilar membrane due to the listener choosing a filter which is centered over the frequency they expect to hear, the signal frequency. A sharply tuned filter has good frequency resolution as it allows the center frequencies through but not other frequencies (Pickles 1982). Damage to the cochlea and the outer hair cells in the cochlea can impair the ability to tell sounds apart (Moore 1986). This explains why someone with a hearing loss due to cochlea damage would have more difficulty than a normal hearing person in distinguishing between different consonants in speech.

Georg von Békésy (, ; born in Budapest, Hungary on 3 June 1899 – 13 June 1972) was a Hungarian biophysicist. By using strobe photography and silver flakes as a marker, he was able to observe that the basilar membrane moves like a surface wave when stimulated by sound. Because of the structure of the cochlea and the basilar membrane, different frequencies of sound cause the maximum amplitudes of the waves to occur at different places on the basilar membrane along the coil of the cochlea. High frequencies cause more vibration at the base of the cochlea while low frequencies create more vibration at the apex.

Békésy contributed most notably to our understanding of the mechanism by which sound frequencies are registered in the inner ear. He developed a method for dissecting the inner ear of human cadavers while leaving the cochlea partly intact. By using strobe photography and silver flakes as a marker, he was able to observe that the basilar membrane moves like a surface wave when stimulated by sound. Because of the structure of the cochlea and the basilar membrane, different frequencies of sound cause the maximum amplitudes of the waves to occur at different places on the basilar membrane along the coil of the cochlea.

It may result from direct injury to the cochlea and spiral ligament from the lytic process or from release of proteolytic enzymes into the cochlea. There are certainly a few well documented instances of sclerotic lesions directly obliterating sensory structures within the cochlea and spiral ligament, which have been photographed and reported post-mortem. Other supporting data includes a consistent loss of cochlear hair cells in patients with otosclerosis; these cells being the chief sensory organs of sound reception. A suggested mechanism for this is the release of hydrolytic enzymes into the inner ear structures by the spongiotic lesions.

Symptoms of ototoxicity include partial or profound hearing loss, vertigo, and tinnitus. The cochlea is primarily a hearing structure situated in the inner ear. It is the snail-shaped shell containing several nerve endings that makes hearing possible. Ototoxicity typically results when the inner ear is poisoned by medication that damages the cochlea, vestibule, semi-circular canals, or the auditory/ vestibulocochlear nerve.

Alternatively, the sensory receivers may be centralized in the cochlea of the inner ear. Vibrations are transmitted from the substrate to the cochlea through the body (bones, fluids, cartilage, etc.) in an ‘extra- tympanic’ pathway that bypasses the eardrum, and sometimes, even the middle ear. Vibrations then project to the brain along with cues from airborne sound received by the eardrum.

The primary function of the middle ear is to efficiently transfer acoustic energy from compression waves in air to fluid–membrane waves within the cochlea.

Boettcher cells are a special cell type located in the inner ear. Boettcher cells are polyhedral cells on the basilar membrane of the cochlea, and are located beneath Claudius cells. Boettcher cells are considered supporting cells for the organ of Corti, and are present only in the lower turn of the cochlea. These cells interweave with each other, and project microvilli into the intercellular space.

Once the sound is able to reach the cochlea at normal or near-normal levels, the cochlea and auditory nerve are able to transmit signals to the brain normally. Common issues with hearing aid fitting and use are the occlusion effect, loudness recruitment, and understanding speech in noise. Once a common problem, feedback is generally now well-controlled through the use of feedback management algorithms.

Hearing impairment may be associated with damage to the hair cells in the cochlea. Sometimes there may be complete loss of function of inner hair cells (IHCs) over a certain region of the cochlea; this is called a "dead region". The region can be defined in terms of the range of characteristic frequencies (CFs) of the IHCs and/or neurons immediately adjacent to the dead region.

SOC, in the pons of the brainstem, travel along the lateral lemniscus to the IC, located in the midbrain. Signals are then relayed to the thalamus and further ascending auditory pathway. As sound travels into the inner eardrum of vertebrate mammals, it encounters the hair cells that line the basilar membrane of the cochlea in the inner ear. The cochlea receives auditory information to be binaurally integrated.

In cases of severe or profound hearing loss, a surgical cochlear implant is possible. This is an electronic device that replaces the cochlea of the inner ear. Electrodes are typically inserted through the round window of the cochlea, into the fluid-filled scala tympani. They stimulate the peripheral axons of the primary auditory neurons, which then send information to the brain via the auditory nerve.

Antibiotics in the aminoglycoside class, such as gentamicin and tobramycin, may produce cochleotoxicity through a poorly understood mechanism. It may result from antibiotic binding to NMDA receptors in the cochlea and damaging neurons through excitotoxicity. Aminoglycoside-induced production of reactive oxygen species may also injure cells of the cochlea. Once-daily dosing and co-administration of N-acetylcysteine may protect against aminoglycoside-induced ototoxicity.

Lera Boroditsky. (1999) "Hearing I: Lecture Notes." pp. 3 Békésy concluded from these observations that by exciting different locations on the basilar membrane different sound wave frequencies excite different nerve fibers that lead from the cochlea to the brain. He theorized that, due to its placement along the cochlea, each sensory cell (hair cell) responds maximally to a specific frequency of sound (the so-called tonotopy).

Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure. Following placement of a ventriculoperitoneal shunt there have been cases of a decrease in post-surgery hearing. It is presumed that the cochlea aqueduct is responsible for the decrease in hearing thresholds. The cochlea aqueduct has been considered as a probable channel where CSF pressure can be transmitted.

The coiled form of cochlea is unique to mammals. In birds and in other non- mammalian vertebrates, the compartment containing the sensory cells for hearing is occasionally also called "cochlea," despite not being coiled up. Instead, it forms a blind-ended tube, also called the cochlear duct. This difference apparently evolved in parallel with the differences in frequency range of hearing between mammals and non-mammalian vertebrates.

Prestin is essential in auditory processing. It is specifically expressed in the lateral membrane of outer hair cells (OHCs) of the cochlea. There is no significant difference between prestin density in high-frequency and low- frequency regions of the cochlea in fully developed mammals. There is good evidence that prestin has undergone adaptive evolution in mammals associated with acquisition of high frequency hearing in mammals.

Changes in pressure caused by sound reaching the external ear resonate in the tympanic membrane, which articulates with the auditory ossicles, or the bones of the middle ear. These tiny bones multiply these pressure fluctuations as they pass the disturbance into the cochlea, a spiral- shaped bony structure within the inner ear. Hair cells in the cochlear duct, specifically the organ of Corti, are deflected as waves of fluid and membrane motion travel through the chambers of the cochlea. Bipolar sensory neurons located in the center of the cochlea monitor the information from these receptor cells and pass it on to the brainstem via the cochlear branch of cranial nerve VIII.

Heteropsammia cochlea, also known as walking dendro, is a species of small solitary coral in the family Dendrophylliidae that is native to the Indo- Pacific area.

In his later work, Bodian studied the spiral structure within the cochlea known as the Organ of Corti as well as the morphology of nerve cells.

Boettcher cells are located immediately under Claudius cells in the lower turn of the cochlea. Claudius cells are named after German anatomist, Friedrich Matthias Claudius (1822–1869).

The active amplifier also leads to the phenomenon of soundwave vibrations being emitted from the cochlea back into the ear canal through the middle ear (otoacoustic emissions).

Figure 3: Cross- section of the cochlea. Outer hair cells (OHCs) contribute to the structure of the Organ of Corti, which is situated between the basilar membrane and the tectorial membrane within the cochlea (See Figure 3). The tunnel of corti, which runs through the Organ of Corti, divides the OHCs and the inner hair cells (IHCs). OHCs are connected to the reticular laminar and the Deiters’ cells.

All of these structures together constitute the cochlea. In mammals (other than monotremes), the cochlea is extended still further, becoming a coiled structure in order to accommodate its length within the head. The organ of Corti also has a more complex structure in mammals than it does in other amniotes. The arrangement of the inner ear in living amphibians is, in most respects, similar to that of reptiles.

Peter Dallos (born November 26, 1934) is the John Evans Professor of Neuroscience Emeritus, Professor Emeritus of Audiology, Biomedical Engineering and Otolaryngology at Northwestern University. His research pertained to the neurobiology, biophysics and molecular biology of the cochlea. This work provided the basis for the present understanding of the role of outer hair cells in hearing, that of providing amplification in the cochlea. After his retirement in 2012, he became a professional sculptor.

The vestibular membrane, vestibular wall or Reissner's membrane, is a membrane inside the cochlea of the inner ear. It separates the cochlear duct from the vestibular duct. Together with the basilar membrane it creates a compartment in the cochlea filled with endolymph, which is important for the function of the spiral organ of Corti. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.

In her laboratory, her group studies the cellular and molecular mechanisms that impact the development of neural circuits. The stages of development being studied are determination, differentiation, how axonal connections are formed, and generation of behavior. Her research program focuses on detecting genes necessary for hearing and balance. Her research hopes to connect molecular pathways that are essential in cochlea development, and to influence these pathways to repair the cochlea after suffering damage.

There can be damage either to the ear, whether the external or middle ear, to the cochlea, or to the brain centers that process the aural information conveyed by the ears. Damage to the middle ear may include fracture and discontinuity of the ossicular chain. Damage to the inner ear (cochlea) may be caused by temporal bone fracture. People who sustain head injury are especially vulnerable to hearing loss or tinnitus, either temporary or permanent.

Efferent projections from the brain to the cochlea also play a role in the perception of sound. Efferent synapses occur on outer hair cells and on afferent axons under inner hair cells. The presynaptic terminal bouton is filled with vesicles containing acetylcholine and a neuropeptide called calcitonin gene-related peptide. The effects of these compounds vary, in some hair cells the acetylcholine hyperpolarized the cell, which reduces the sensitivity of the cochlea locally.

The inner ear structurally begins at the oval window, which receives vibrations from the incus of the middle ear. Vibrations are transmitted into the inner ear into a fluid called endolymph, which fills the membranous labyrinth. The endolymph is situated in two vestibules, the utricle and saccule, and eventually transmits to the cochlea, a spiral-shaped structure. The cochlea consists of three fluid-filled spaces: the vestibular duct, the cochlear duct, and the tympanic duct.

Otoacoustic emissions are due to a wave exiting the cochlea via the oval window, and propagating back through the middle ear to the eardrum, and out the ear canal, where it can be picked up by a microphone. Otoacoustic emissions are important in some types of tests for hearing impairment, since they are present when the cochlea is working well, and less so when it is suffering from loss of OHC activity.

Gap-junction proteins, called connexins, expressed in the cochlea play an important role in auditory functioning. Mutations in gap-junction genes have been found to cause syndromic and nonsyndromic deafness. Certain connexins, including connexin 30 and connexin 26, are prevalent in the two distinct gap-junction systems found in the cochlea. The epithelial-cell gap-junction network couples non-sensory epithelial cells, while the connective-tissue gap-junction network couples connective-tissue cells.

Research on the olfactory bulbs has shown that T. rex had the most highly developed sense of smell of 21 sampled non-avian dinosaur species. Cast of the braincase at the Australian Museum, Sydney. Somewhat unusually among theropods, T. rex had a very long cochlea. The length of the cochlea is often related to hearing acuity, or at least the importance of hearing in behavior, implying that hearing was a particularly important sense to tyrannosaurs.

There can be damage either to the ear, whether the external or middle ear, to the cochlea, or to the brain centers that process the aural information conveyed by the ears. Damage to the middle ear may include fracture and discontinuity of the ossicular chain. Damage to the inner ear (cochlea) may be caused by temporal bone fracture. People who sustain head injury are especially vulnerable to hearing loss or tinnitus, either temporary or permanent.

Goldstein, B. 2001. Sensation and Perception, 6th ed. London: Wadsworth. High frequencies cause more vibration at the base of the cochlea while low frequencies create more vibration at the apex.

The hypothesised functions of the MOCS fall into three general categories; (i) cochlear protection against loud sounds, (ii) development of cochlea function, and (iii) detection and discrimination of sounds in noise.

It has been proposed that tinnitus is caused by mechanisms that generate abnormal neural activity, specifically one mechanism called discordant damage (dysfunction) of outer and inner hair cells of the cochlea.

Medial to the opening for the carotid canal and close to its posterior border, in front of the jugular fossa, is a triangular depression; at the apex of this is a small opening, the aquaeductus cochleae (or cochlear aqueduct, or aqueduct of cochlea), which lodges a tubular prolongation of the dura mater establishing a communication between the perilymphatic space and the subarachnoid space, and transmits a vein from the cochlea to join the internal jugular vein.

The cochlea is a spiral-shaped, fluid-filled tube divided lengthwise by the organ of Corti which contains the basilar membrane. The basilar membrane increases in thickness as it travels through the cochlea causing different frequencies to resonate at different locations. This tonotopic design allows for the ear to analyze sound in a manner similar to a Fourier transform. The differential vibration of the basilar causes the hair cells within the organ of Corti to move.

EP44 receptors are expressed in the cochlea of the inner ear. Pre- and post-treatment of guinea pigs with an EP4 agonist significantly attenuated threshold shifts of auditory brain stem responses and significantly reduced the loss of outer hair cells caused by prior noise exposure. These findings indicate that EP4 is involved in mechanisms for prostaglandin E(1) actions on the cochlea, and local EP4 agonist treatment may be a means for attenuating noise-induced hearing lose.

Figure 1: Interaural attenuation with air conduction. Figure 2: Interaural attenuation with bone conduction When sound is applied to one ear the contralateral cochlea can also be stimulated to varying degrees, via vibrations through the bone of the skull. When the stimuli presented to the test ear stimulates the cochlea of the non-test ear, this is known as cross hearing. Whenever it is suspected that cross hearing has occurred it is best to use masking.

The human cochlea has approximately 2.5 turns around the modiolus (the axis). Humans, like many mammals and birds, are able to perceive auditory signals that displace the eardrum by a mere picometre.

This tonotopy plays a crucial role in hearing, as it allows for spectral separation of sounds. A cross section of the cochlea will reveal an anatomical structure with three main chambers (scala vestibuli, scala media, and scala tympani). At the apical end of the cochlea, at an opening known as the helicotrema, the scala vestibuli merges with the scala tympani. The fluid found in these two cochlear chambers is perilymph, while scala media, or the cochlear duct, is filled with endolymph.

This claim (that MOC-mediated cochlear protection is an epiphenomenon) was recently challenged by Darrow et al. (2007), who suggested that the LOCS has an anti-excitotoxic effect, indirectly protecting the cochlea from damage.

The spiral shape of the cochlea evolved later on in the evolutionary pathway of mammals than previously believed, just before the therians split into the two lineages marsupials and placentals, about 120 million years ago.

Heteropsammia corals (of the species Heteropsammia cochlea) have been observed ingesting salps in Leuk Bay, Koh Tao, Gulf of Thailand, thanks to their large gape, as the salps were larger than the corals mouth opening.

The cochlear amplifier was first proposed in 1948 by Gold.T. Gold 1948 : Hearing. II. The Physical Basis of the Action of the Cochlea This was around the time when Georg von Békésy was publishing articles observing the propagation of passive travelling waves in the dead cochlea. Thirty years later the first recordings of emissions from the ear were captured by Kemp.D. T. Kemp 1978 : Stimulated acoustic emissions from within the human auditory system This was confirmation that such an active mechanism was present in the ear.

The retinoblastoma protein is involved in the growth and development of mammalian hair cells of the cochlea, and appears to be related to the cells' inability to regenerate. Embryonic hair cells require Rb, among other important proteins, to exit the cell-cycle and stop dividing, which allows maturation of the auditory system. Once wild-type mammals have reached adulthood, their cochlear hair cells become incapable of proliferation. In studies where the gene for Rb is deleted in mice cochlea, hair cells continue to proliferate in early adulthood.

Further, the auditory innervation of the spiral-shaped cochlea also traces back to the Cretaceous period. The evolution of the human cochlea is a major area of scientific interest because of its favourable representation in the fossil record. During the last century, many scientists such as evolutionary biologists and paleontologists strove to develop new methods and techniques to overcome the many obstacles associated with working with ancient, delicate artifacts. In the past, scientists were limited in their ability to fully examine specimens without causing damage to them.

The development of the most basic basilar papilla (the auditory organ that later evolved into the Organ of Corti in mammals) happened at the same time as the water-to-land transition of vertebrates, approximately 380 million years ago. The actual coiling or spiral nature of the cochlea occurred to save space inside the skull. The longer the cochlea, the higher is the potential resolution of sound frequencies given the same hearing range. The oldest of the truly coiled mammalian cochleae were approximately 4 mm in length.

Parallel to the evolution of the cochlea, prestin shows an increased rate of evolution in therian mammals. Prestin is the motor protein of the outer hair cells of the inner ear of the mammalian cochlea. It is are found in the hair cells of all vertebrates, including fish, but are thought to have initially been membrane transporter molecules. A high concentration of prestin are found only in the lateral membranes of therian outer hair cells (there is uncertainty with regard to concentrations in monotremes).

In one 1997 study of white cats, 72% of the animals were found to be totally deaf. The entire organ of Corti in the cochlea was found to have degenerated in the first few weeks after birth; however, even during these weeks no brain stem responses could be evoked by auditory stimuli, suggesting that these animals had never experienced any auditory sensations. It was found that some months after the organ of Corti had degenerated, the spiral ganglion of the cochlea also began to degenerate.

In 1988, Richard F. Lyon and Carver Mead described the creation of an analog cochlea, modelling the fluid-dynamic traveling-wave system of the auditory portion of the inner ear. Lyon had previously described a computational model for the work of the cochlea.Richard F. Lyon, "A Computational Model of Filtering, Detection, and Compression in the Cochlea", Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing, Paris, May 1982. Such technology had potential applications in hearing aids, cochlear implants, and a variety of speech-recognition devices.

Single- sided deafness (SSD) and conductive hearing loss (CHL) are life-altering conditions where patients often have anxiety, depression, social isolation, and reduced quality of life. SSD patients have one cochlea that is virtually non-functional. It does not hear sound even when using conventional hearing aids, which are amplification devices that simply “turn up the volume” on air- conducted sound. CHL patients have a problem with the ear (outer, middle or canal) that prohibits air conducted sound from reaching an otherwise functional cochlea.

Rasp built a work group and assisted 21 dissertations and two habilitations. In 1997 he reached venia legendi as Dr. med. habil. and was named '"Privatdozent". He took over cochlea implementation at the hospital for otorhinolaryngology.

As with any type of hearing-related disorder, the related physiology is within the ear and central auditory system. With regards to listening fatigue, the relevant mechanical and biochemical mechanisms primarily deal with inner ear and cochlea.

The scala vestibuli and scala media are separated by Reissner's Membrane whereas the scala media and scala tympani are divided by the basilar membrane. The diagram below illustrates the complex layout of the compartments and their divisions: Cross-section through the cochlea, showing the different compartments (as described above) The basilar membrane widens as it progresses from base to apex. Therefore, the base (the thinnest part) has a greater stiffness than the apex. This means that the amplitude of a sound wave travelling through the basilar membrane varies as it travels through the cochlea.

This gene is a member of the ligand-gated ionic channel family and nicotinic acetylcholine receptor gene superfamily. It encodes a plasma membrane protein that forms homo- or hetero-oligomeric divalent cation channels. This protein is involved in cochlea hair cell function and is expressed in both the inner and outer hair cells (OHCs) of the adult cochlea, although expression levels in adult inner hair cells is low. The activation of the alpha9/10 nAChR is via olivocochlear activity, represented by cholinergic efferent synaptic terminals originating from the superior olive region of the brainstem.

When comparing hominins of the Middle Pleistocene, Neanderthals and Holocene humans, the apex of the cochlea faces more inferiorly in the hominins than the latter two groups. Finally, the cochlea of European middle Pleistocene hominins faces more inferiorly than Neanderthals, modern humans, and Homo erectus. Human beings, along with apes, are the only mammals that do not have high frequency (>32 kHz) hearing. Humans have long cochleae, but the space devoted to each frequency range is quite large (2.5mm per octave), resulting in a comparatively reduced upper frequency limit.

When interpreting the ABR, we look at amplitude (the number of neurons firing), latency (the speed of transmission), interpeak latency (the time between peaks), and interaural latency (the difference in wave V latency between ears). The ABR represents initiated activity beginning at the base of the cochlea and moving toward the apex over a 4ms period of time. The peaks largely reflect activity from the most basal regions on the cochlea because the disturbance hits the basal end first and by the time it gets to the apex, a significant amount of phase cancellation occurs.

A direct acoustic cochlear implant - also DACI - is an acoustic implant which converts sound in mechanical vibrations that stimulate directly the perilymph inside the cochlea. The hearing function of the external and middle ear is being taken over by a little motor of a cochlear implant, directly stimulating the cochlea. With a DACI, people with no or almost no residual hearing but with a still functioning inner ear, can again perceive speech, sounds and music. DACI is an official product category, as indicated by the nomenclature of GMDN.

Békésy later developed a mechanical model of the cochlea, which confirmed the concept of frequency dispersion by the basilar membrane in the mammalian cochlea. In an article published posthumously in 1974, Békésy reviewed progress in the field, remarking "In time, I came to the conclusion that the dehydrated cats and the application of Fourier analysis to hearing problems became more and more a handicap for research in hearing," referring to the difficulties in getting animal preparations to behave as when alive, and the misleading common interpretations of Fourier analysis in hearing research.

The chemical difference between the fluids endolymph and perilymph fluids is important for the function of the inner ear due to electrical potential differences between potassium and calcium ions. The plan view of the human cochlea (typical of all mammalian and most vertebrates) shows where specific frequencies occur along its length. The frequency is an approximately exponential function of the length of the cochlea within the Organ of Corti. In some species, such as bats and dolphins, the relationship is expanded in specific areas to support their active sonar capability.

William House also invented a cochlear implant in 1961. In 1964, Blair Simmons and Robert J. White implanted a single-channel electrode in a patient's cochlea at Stanford University. However, research indicated that these single-channel cochlear implants were of limited usefulness because they can not stimulate different areas of the cochlea at different times to allow differentiation between low and mid to high frequencies as required for detecting speech. NASA engineer Adam Kissiah started working in the mid-1970s on what could become the modern cochlear implant.

The tonotopic layout of sound information begins in the cochlea where the basilar membrane vibrates at different positions along its length depending upon the frequency of the sound. Higher frequency sounds are at the base of the cochlea, if it were unrolled, and low frequency sounds are at the apex. This arrangement is also found in the auditory cortex in the temporal lobe. In areas that are tonotopically organized, the frequency varies systematically from low to high along the surface of the cortex, but is relatively constant across cortical depth.

The cochlear nerve spans from the cochlea of the inner ear to the ventral cochlear nuclei located in the pons of the brainstem, relaying auditory signals to the superior olivary complex where it is to be binaurally integrated.

Hearing Research. 2000;145(1-2):111-122.Wang Y, Hirose K, Liberman MC. Dynamics of Noise-Induced Cellular Injury and Repair in the Mouse Cochlea. JARO - Journal of the Association for Research in Otolaryngology. 2002;3(3):248-268.

These hearing aids are also used for people with severe hearing loss. Baha hearing aids attach to the bones of the middle ear to create the sound vibrations in the skull and send those vibrations to the cochlea.

Suppressing function of the retinoblastoma protein in the adult rat cochlea has been found to cause proliferation of supporting cells and hair cells. Rb can be downregulated by activating the sonic hedgehog pathway, which phosphorylates the proteins and reduces gene transcription.

Obtainium is an album by Skeleton Key, released in 2002 by Ipecac Recordings. The image on the CD is a representation of the bones of the inner ear, including the cochlea. The name is a play on the fictional element unobtainium.

Those transmissions then travel through skull foramina into the skull cavity. From there, they channel into the inner ear fluids, stimulating the cochlea. Subsequently, Sonitus Medical developed SoundBite Hearing System to use those principles in a non-surgical, removable hearing system.

The placement of vibration on the cochlea depends upon the frequency of the presented stimuli. For example, lower frequencies mostly stimulate the apex, in comparison to higher frequencies, which stimulate the base of the cochlea. This attribute of the physiology of the basilar membrane can be illustrated in the form of a place–frequency map: Simplified schematic of the basilar membrane, showing the change in characteristic frequency from base to apex The basilar membrane supports the organ of Corti, which sits within the scala media. The organ of Corti comprises both outer and inner hair cells.

Thresholds at low frequency dead regions, are more inaccurate than those at higher frequency dead regions. This has been attributed to the fact that excitation due to vibration of the basilar membrane spreads upwards from the apical regions of the basilar membrane, more than excitation spreads downwards from higher frequency basal regions of the cochlea. This pattern of the spread of excitation is similar to the ‘upward spread of masking’ phenomenon. If the tone is sufficiently loud to produce enough excitation at the normally functioning area of the cochlea, so that it is above that areas threshold.

The stapes bone transmits movement to the oval window. As the stapes footplate moves into the oval window, the round window membrane moves out, and this allows movement of the fluid within the cochlea, leading to movement of the cochlear inner hair cells and thus hearing. If the round window were to be absent or rigidly fixed (as can happen in some congenital abnormalities), the stapes footplate would be pushing incompressible fluid against the unyielding walls of the cochlea. It would therefore not move to any useful degree leading to a hearing loss of about 60dB.

One such mechanism is the opening of ion channels in the hair cells of the cochlea in the inner ear. Air pressure changes in the ear canal cause the vibrations of the tympanic membrane and middle ear ossicles. At the end of the ossicular chain, movement of the stapes footplate within the oval window of the cochlea, in turn, generates a pressure field within the cochlear fluids, imparting a pressure differential across the basilar membrane. A sinusoidal pressure wave results in localized vibrations of the organ of Corti: near the base for high frequencies, near the apex for low frequencies.

The proportion of fibres in the MOCS and LOCS also varies between species, but in most cases the fibres of the LOCS are more numerous.Robertson et al., 1989 In humans, there are an estimated (average) 1,000 LOCS fibres and 360 MOCS fibres, however the numbers vary between individuals. The MOCS gives rise to a frequency-specific innervation of the cochlea, in that MOC fibres terminate on the outer hair cells at the place in the cochlea predicted from the fibres’ characteristic frequency, and are thus tonotopically organised in the same fashion as the primary afferent neurons.

Megabats are the only family of bats incapable of laryngeal echolocation. It is unclear whether the common ancestor of all bats was capable of echolocation, and thus echolocation was lost in the megabat lineage, or multiple bat lineages independently evolved the ability to echolocate (the superfamily Rhinolophoidea and the suborder Yangochiroptera). This unknown element of bat evolution has been called a "grand challenge in biology". A 2017 study of bat ontogeny (embryonic development) found evidence that megabat embryos at first have large, developed cochlea similar to echolocating microbats, though at birth they have small cochlea similar to non-echolocating mammals.

The tectorial membrane (TM) is one of two acellular membranes in the cochlea of the inner ear, the other being the basilar membrane (BM). "Tectorial" in anatomy means forming a cover. The TM is located above the spiral limbus and the spiral organ of Corti and extends along the longitudinal length of the cochlea parallel to the BM. Radially the TM is divided into three zones, the limbal, middle and marginal zones. Of these the limbal zone is the thinnest (transversally) and overlies the auditory teeth of Huschke with its inside edge attached to the spiral limbus.

Harbour porpoises emit sounds at two bands, one at 2 kHz and one above 110 kHz. The cochlea in these dolphins is specialised to accommodate extreme high frequency sounds and is extremely narrow at the base. Type II cochlea are found primarily in offshore and open water species of whales, such as the bottlenose dolphin. The sounds produced by bottlenose dolphins are lower in frequency and range typically between 75 and 150,000 Hz. The higher frequencies in this range are also used for echolocation and the lower frequencies are commonly associated with social interaction as the signals travel much farther distances.

Connexin 26 and connexin 30 are commonly accepted to be the predominant gap junction proteins in the cochlea. Genetic knockout experiments in mice has shown that knockout of either Cx26 or Cx30 produces deafness. However, recent research suggests that Cx30 knockout produces deafness due to subsequent downregulation of Cx26, and one mouse study found that a Cx30 mutation that preserves half of Cx26 expression found in normal Cx30 mice resulted in unimpaired hearing. The lessened severity of Cx30 knockout in comparison to Cx26 knockout is supported by a study examining the time course and patterns of hair cell degeneration in the cochlea.

OAEs are a measurement of the activity of outer hair cells in the cochlea, and noise- induced hearing loss occurs as a result of damage to the outer hair cells in the cochlea. Therefore, the damage or loss of some outer hair cells will likely show up on OAEs before showing up on the audiogram. Studies have shown that for some individuals with normal hearing that have been exposed to excessive sound levels, fewer, reduced, or no OAEs can be present. This could be an indication of noise-induced hearing loss before it is seen on an audiogram.

The cochlear duct (or scala media) is an endolymph filled cavity inside the cochlea, located between the tympanic duct and the vestibular duct, separated by the basilar membrane and Reissner's membrane (the vestibular membrane) respectively. The cochlear duct houses the organ of Corti.

In 2009, engineers at the Massachusetts Institute of Technology created an electronic chip that can quickly analyze a very large range of radio frequencies while using only a fraction of the power needed for existing technologies; its design specifically mimics a cochlea.

Cav1.3 channels are widely expressed in humans. Notably, their expression predominates in cochlea inner hair cells (IHCs). Cav1.3 have been shown through patch clamp experiments to be essential for normal IHC development and synaptic transmission. Therefore, Cav1.3 are required for proper hearing.

He attended Harvard University after completing his military service in 1946, and was awarded a Ph.D. in 1949. His thesis showed that the connections between the cochlea and the cerebral cortex could be monitored using electrodes placed on the scalp, without requiring cranial surgery.

Lack of CDKN1B expression appears to release the hair cells from natural cell-cycle arrest. Because hair cell death in the human cochlea is a major cause of hearing loss, the CDKN1B protein could be an important factor in the clinical treatment of deafness.

This gene encodes an unconventional myosin. This protein differs from other myosins in that it has a long N-terminal extension preceding the conserved motor domain. Studies in mice suggest that this protein is necessary for actin organization in the hair cells of the cochlea.

The round window is located within the mesotympanum, at the posterior extremity of the basal turn of the cochlea. The oval windows is also located within the mesotympanum, opening at the inferior and lateral part of the vestibule. Both can be seen readily on CT.

SLC26A4 can be found in the cochlea (part of the inner ear), thyroid and the kidney. In the kidney, it participates in the secretion of bicarbonate. However, Pendred syndrome is not known to lead to kidney problems. It functions as an iodide/chloride transporter.

The Cochlea Volume 8 in: Springer Handbook of Auditory Research, series editors A. Popper and R. Fay (Springer-Verlag, New York, 1996, 551 pages). Dallos, P. and D. Oertel, Edts. Hearing, in the series The Senses: A Comprehensive Reference (Elsevier, London, 2007, 970 pages).

Their work has inspired ongoing research attempting to create a silicon analog that can emulate the signal processing capacities of a biological cochlea. In 1991, Mead helped to form Sonix Technologies, Inc. (later Sonic Innovations Inc.). Mead designed the computer chip for their hearing aids.

The vestibule is the central part of the bony labyrinth in the inner ear, and is situated medial to the eardrum (tympanic cavity), behind the cochlea, and in front of the three semicircular canals. The name comes from the Latin vestibulum, literally an entrance hall.

In 1975, the Austrian Research Council supported Hochmair's cochlear implant project by a grant of 110,000 ATS, roughly equivalent to $11,000 USD. Together with his wife Ingeborg Hochmair, who holds several degrees in electrical engineering, he designed a device that was able to stimulate the fibers of the auditory nerve at several locations within the cochlea. A previous implant design by William F. House could only stimulate cochlea at one site. They built a multichannel intra-cochlear electrode, and developed all the implantable and the external electronics for the transcutaneous transmission, the coding and decoding of circuits and the electrode driving circuitry while trying to minimize the power consumption.

Egg-laying mammals, the monotremes (echidna and platypus), do not have a spiral cochlea, but one shaped more like a banana, up to about 7 mm long. Like in lepidosaurs and archosaurs, it contains a lagena, a vestibular sensory epithelium, at its tip. Only in therian mammals (marsupials and placentals) is the cochlea truly coiled 1.5 to 3.5 times. Whereas in monotremes there are many rows of both inner and outer hair cells in the organ of Corti, in therian (marsupial and placental) mammals the number of inner hair-cell rows is one, and there are generally only three rows of outer hair cells.

The most prominent figure in the creation of the place theory of hearing is Hermann von Helmholtz, who published his finished theory in 1885. Helmholtz claimed that the cochlea contained individual fibers for analyzing each pitch and delivering that information to the brain. Many followers revised and added to Helmholtz's theory and the consensus soon became that high frequency sounds were encoded near the base of the cochlea and that middle frequency sounds were encoded near the apex. Georg von Békésy developed a novel method of dissecting the inner ear and using stroboscopic illumination to observe the basilar membrane move, adding evidence to support the theory.

The cochlear amplifier is a positive feedback mechanism within the cochlea that provides acute sensitivity in the mammalian auditory system. The main component of the cochlear amplifier is the outer hair cell (OHC) which increases the amplitude and frequency selectivity of sound vibrations using electromechanical feedback.

Avian hair cells have been extensively studied in the cochlea of the barn owl,Konishi, M., T.T. Takahashi, H. Wagner, W.E. Sullivan and C.E. Carr. 1988. Neurophysiological and anatomical substrates of sound localization in the owl. In “Auditory Function”. G.M. Edelman, W.E. Gall and W.M. Cowan, Eds.

A recessive mutation in this gene called IVS12+2T>C results in deafness. The human protein has 1,153 amino acids. In the mouse, this protein has 1088 amino acids. In mice otoancorin is needed to attach the tectorial membrane to the inner hair cells in the cochlea.

There is variable penetrance and variable gene expression within these genetic mutations. Individuals with sensorineural hearing loss are believed to have a local lesion in the auditory segment of the inner ear, known as the cochlea. The biological mechanism for this is currently unknown as well.

The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain. Through olivocochlear fibers, this nerve also transmit motor and modulatory information from the superior olivary complex in the brainstem to the cochlea.

In humans, sound waves funnel into the ear via the external ear canal and reach the eardrum (tympanic membrane). The compression and rarefaction of these waves set this thin membrane in motion, causing sympathetic vibration through the middle ear bones (the ossicles: malleus, incus, and stapes), the basilar fluid in the cochlea, and the hairs within it, called stereocilia. These hairs line the cochlea from base to apex, and the part stimulated and the intensity of stimulation gives an indication of the nature of the sound. Information gathered from the hair cells is sent via the auditory nerve for processing in the brain. The commonly stated range of human hearing is 20 to 20,000 Hz.20 to 20,000 Hz corresponds to sound waves in air at 20°C with wavelengths of 17 meters to 1.7 cm (56 ft to 0.7 inch). Under ideal laboratory conditions, humans can hear sound as low as 12 Hz and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea.

The protein encoded by this gene plays an important role in hearing in humans. Three different recessive, loss of function mutations in the encoded protein have been shown to cause nonsyndromic progressive hearing loss. Expression of this gene is highly restricted, with the strongest expression in retina and cochlea.

All mammalian organs of Corti contain a supporting tunnel made up of pillar cells, on the inner side of which there are inner hair cells and outer hair cells on the outer side. The definitive mammalian middle ear and the elongated cochlea allows for better sensitivity for higher frequencies.

The disproportionate number of receptors in the cochlea that respond to frequencies within a narrow range ultimately gives rise to the acoustic fovea. This cochlear morphology is the anatomical correlate of the acoustic fovea. As a result, bats are able to respond preferentially to sounds of these frequencies.

In 1886, Rutherford also proposed that the brain interpreted the vibrations of the hair cells and that the cochlea did no frequency or pitch analysis of the sound. Soon after, Max Friedrich Meyer, among other ideas, theorized that nerves would be excited at the same frequency of the stimulus.

The dorsal cochlear nucleus (DCN, also known as the "tuberculum acusticum"), is a cortex-like structure on the dorso-lateral surface of the brainstem. Along with the ventral cochlear nucleus (VCN), it forms the cochlear nucleus (CN), where all auditory nerve fibers from the cochlea form their first synapses.

The cochlea thus acts as an 'acoustic prism', distributing the energy of each Fourier component of a complex sound at different locations along its longitudinal axis. Hair cells in the cochlea are stimulated when the basilar membrane is driven up and down by differences in the fluid pressure between the scala vestibuli and scala tympani. Because this motion is accompanied by a shearing motion between the tectorial membrane and the reticular lamina of the organ of Corti, the hair bundles that link the two are deflected, which initiates mechano-electrical transduction. When the basilar membrane is driven upward, shear between the hair cells and the tectorial membrane deflects hair bundles in the excitatory direction, toward their tall edge.

Projecting from the tops of the hair cells are tiny finger like projections called stereocilia, which are arranged in a graduated fashion with the shortest stereocilia on the outer rows and the longest in the center. This gradation is thought to be the most important anatomic feature of the organ of Corti because this allows the sensory cells superior tuning capability. If the cochlea were uncoiled, it would roll out to be about 33 mm long in women and 34 mm in men, with about 2.28 mm of standard deviation for the population. The cochlea is also tonotopically organized, meaning that different frequencies of sound waves interact with different locations on the structure.

Clark hypothesised that hearing, particularly for speech, might be reproduced in people with deafness if the damaged or underdeveloped ear were bypassed, and the auditory nerve electrically stimulated to reproduce the coding of sound. His initial doctoral research at the University of Sydney investigated the effect of the rate of electrical simulation on single cells and groups of cells in the auditory brainstem response, the centre where frequency discrimination is first decoded. Clark's research demonstrated that an electrode bundle with 'graded stiffness' would pass without injury around the tightening spiral of the cochlea to the speech frequency region. Until this time he had difficulty identifying a way to place the electrode bundle in the cochlea without causing any damage.

This test helps the audiologist determine whether the hearing loss is conductive (caused by problems in the outer or middle ear) or sensorineural (caused by problems in the cochlea, the sensory organ of hearing) or neural - caused by a problem in the auditory nerve or auditory pathways/cortex of the brain.

These simultaneous sounds are evaluated and grouped by source. In doing this, the microphones of a mobile device, together with Audience's proprietary "Fast Cochlea Transform" technology, can identify and group sounds which are classified as noise, remove or at least reduce them, and leave the remaining clear voice signal intact.

Nobel lecture of R. A. Zsigmondy: Properties of colloids (including a short explanation of the ultramicroscope) The first application of this illumination scheme for fluorescence microscopy was published in 1993 by Voie et al. under the name orthogonal-plane fluorescence optical sectioning (OPFOS). for imaging of the internal structure of the cochlea.

These movements are very small, like vibrations and are transmitted to the inner ear. 3\. The inner ear contains a structure called the cochlea, which contains small hair- like cells that respond to sound information and transmits it via nerve impulses down the auditory nerve and to the brain, where they are processed.

Crawford is known for his studies of the mechanism of hearing in vertebrates. In 1976, he and Robert Fettiplace developed a method of recording the electrical responses of hair cells in the isolated cochlea of reptiles. He has also published a series of important papers on neuromuscular transmission in frogs and crabs.

The vestibular system helps a person maintain: balance, visual fixation, posture, and lower muscular control. There are six receptor organs located in the inner ear: cochlea, utricle, saccule, and the lateral, anterior, and posterior semicircular canals. The cochlea is a sensory organ with the primary purpose to aid in hearing. The otolith organs (utricle and saccule) are sensors for detecting linear acceleration in their respective planes (utrical=horizontal plane (forward/backward; up/down); saccule=sagital plane (up/down)), and the three semicircular canals (anterior/superior, posterior, and horizontal) detect head rotation or angular acceleration in their respective planes of orientation (anterior/superior=pitch (nodding head), posterior=roll (moving head from one shoulder to other), and horizontal=yaw (shaking head left to right).

Based on clinical testing of subjects with auditory neuropathy, the disruption in the stream of sound information has been localized to one or more of three probable locations: the inner hair cells of the cochlea, the synapse between the inner hair cells and the auditory nerve, or a lesion of the ascending auditory nerve itself.

The stacked ABR is the sum of the synchronous neural activity generated from five frequency regions across the cochlea in response to click stimulation and high-pass pink noise masking. The development of this technique was based on the 8th cranial nerve compound action potential work done by Teas, Eldredge, and Davis in 1962.

The sound in the tympanic membrane is converted into vibrations (kinetic energy) via the three interconnecting ear ossicles to the oval window of the inner ear. The middle ear is connected to the perilymph (fluid) of the inner ear via the oval window. The oval window has the ability to hold fluid in the cochlea.

It is affected by the closing mechanism of the mechanical sensory ion channels at the tips of the hair bundles. The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals that are then relayed via the auditory nerve to the auditory brainstem and to the auditory cortex.

The protein encoded by this gene forms a potassium channel that is thought to play a critical role in the regulation of neuronal excitability, particularly in sensory cells of the cochlea. The encoded protein can form a homomultimeric potassium channel or possibly a heteromultimeric channel in association with the protein encoded by the KCNQ3 gene.

The inner ear has two major parts, the cochlea and the vestibular organ. They are connected in a series of canals in the temporal bone referred to as the bony labyrinth. The bone canals are separated by the membranes in parallel spaces referred to as the membranous labyrinth. The membranous contains two fluids called perilymph and endolymph.

Fountain syndrome is an autosomal recessive congenital disorder characterized by mental retardation, deafness, skeletal abnormalities and a coarse face with full lips. The abnormal swelling of the cheeks and lips are due to the excessive accumulation of body fluids under the skin. The deafness is due to malformation of the cochlea structure within the inner ear.

These leverage the larger motions of the eardrum to the smaller vibrations of the oval window. This window connects to the cochlea which is a long dual channel arrangement consisting of two channels separated by the basilar membrane. The structure, about 36 mm in length, is coiled to conserve space. The oval window introduces sounds to the upper channel.

The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss. The term "ossicle" literally means "tiny bone".

They do this by transducing mechanical movements or signals into neural activity. When stimulated, the stereocilia on the IHCs move, causing a flow of electric current to pass through the hair cells. This electric current creates action potentials within the connected afferent neurons. OHCs are different in that they actually contribute to the active mechanism of the cochlea.

Myosin III is a poorly understood member of the myosin family. It has been studied in vivo in the eyes of Drosophila, where it is thought to play a role in phototransduction. A human homologue gene for myosin III, MYO3A, has been uncovered through the Human Genome Project and is expressed in the retina and cochlea.

Claudius cells are considered as supporting cells within the organ of Corti in the cochlea. These cells extend from Hensen's cells to the spiral prominence epithelium, forming the outer sulcus. They are in direct contact with the endolymph of the cochlear duct. These cells are sealed via tight junctions that prevent flow of endolymph between them.

A hearing aid also simply provides more loudness, no more resolution. Users will view this often as, "all sounds louder, but I understand nothing more than before." Once a hearing aid offers no solution anymore, one can switch to a cochlear implant. A Cochlear implant captures the sound and sends it electrically, through the cochlea, to the auditory nerve.

The middle avian ear is made up of three semicircular canals, each ending in an ampulla and joining to connect with the macula sacculus and lagena, of which the cochlea, a straight short tube to the external ear, branches from. Birds have a large brain to body mass ratio. This is reflected in the advanced and complex bird intelligence.

The Kresge Hearing Research Institute is an institute of Otolaryngology of the Department of Otolaryngology in the University of Michigan. The research institute was officially opened in 1963 to investigate the human hearing and causes of deafness. In 2005, the discovery of being able to regrow cochlea hair nerves in guinea pigs at KHRI made international news.

Dr Sandra Desa Souza is an ENT Head, Neck and Cochlea Implant Surgeon. She is the first Indian Fellow of the American Otological Society. She was awarded the Padma Shri India's fourth-highest civilian award in 2020. She is the first woman surgeon in the world to pioneer the Cochlear implant surgery in India and Asia in 1987.

It transmits vibrations to the incus, which in turn transmits the vibrations to the small stapes bone. The wide base of the stapes rests on the oval window. As the stapes vibrates, vibrations are transmitted through the oval window, causing movement of fluid within the cochlea. The round window allows for the fluid within the inner ear to move.

There are three semicircular canals angled at right angles to each other which are responsible for dynamic balance. The cochlea is a spiral shell-shaped organ responsible for the sense of hearing. These structures together create the membranous labyrinth. The bony labyrinth refers to the bony compartment which contains the membranous labyrinth, contained within the temporal bone.

The apertures in the pyramid transmit the nerves to the utricle; those in the recessus ellipticus are the nerves to the ampullæ of the superior and lateral semicircular ducts. Behind, the five orifices of the semicircular canals can be found. In the frontal view, there is an elliptical opening which communicates with the scala vestibuli of the cochlea.

They control the contraction of smooth muscle and are involved with the electrical tuning of hair cells in the cochlea. BK channels also contribute to the behavioral effects of ethanol in the worm C. elegans under high concentrations (> 100 mM, or approximately 0.50% BAC). It remains to be determined if BK channels contribute to intoxication in humans.

This is due to abnormality in cochlea such as hypersensitivity of haircells due to damage. Recruitment is a landmark feature of SNHL of cochlear origin. Reverse Recruitment / Decruitment is a hallmark feature of SNHL of Retro Cochlear region. When recruitment is found to be associated with presence of cochlear pathology then the recruitment is known as complete recruitment.

The most common form of hearing loss for which hearing aids are sought is sensorineural, resulting from damage to the hair cells and synapses of the cochlea and auditory nerve. Sensorineural hearing loss reduces the sensitivity to sound, which a hearing aid can partially accommodate by making sound louder. Other decrements in auditory perception caused by sensorineural hearing loss, such as abnormal spectral and temporal processing, and which may negatively affect speech perception, are more difficult to compensate for using digital signal processing and in some cases may be exacerbated by the use of amplification. Conductive hearing losses, which do not involve damage to the cochlea, tend to be better treated by hearing aids; the hearing aid is able to sufficiently amplify sound to account for the attenuation caused by the conductive component.

At the cochlea, this information is converted into electrical impulses that travel by means of the cochlear nerve, which spans from the cochlea to the ventral cochlear nucleus, which is located in the pons of the brainstem. The lateral lemniscus projects from the cochlear nucleus to the superior olivary complex (SOC), a set of brainstem nuclei that consists primarily of two nuclei, the medial superior olive (MSO) and the lateral superior olive (LSO), and is the major site of binaural fusion. The subdivision of the ventral cochlear nucleus that concerns binaural fusion is the anterior ventral cochlear nucleus (AVCN). The AVCN consists of spherical bushy cells and globular bushy cells and can also transmit signals to the medial nucleus of the trapezoid body (MNTB), whose neuron projects to the MSO.

The LOCS (originating from both the intrinsic and shell neurons) contains unmyelinated fibres that synapse with the dendrites of the Type I spiral ganglion cells projecting to the inner hair cells. While the intrinsic LOCS neurons tend to be small (~10 to 15 µm in diameter), and the shell OC neurons are larger (~25 µm in diameter), it is the intrinsic OC neurons that possess the larger axons (0.77 µm compared to 0.37 µm diameter for shell neurons). In contrast, the MOCS contains myelinated nerve fibres which innervate the outer hair cells directly. Although both the LOCS and MOCS contain crossed (contralateral) and uncrossed (ipsilateral) fibres, in most mammalian species the majority of LOCS fibres project to the ipsilateral cochlea, whilst the majority of the MOCS fibres project to the contralateral cochlea.

The farther a wave travels towards the cochlea's apex (the helicotrema), the less stiff the basilar membrane is; thus lower frequencies travel down the tube, and the less-stiff membrane is moved most easily by them where the reduced stiffness allows: that is, as the basilar membrane gets less and less stiff, waves slow down and it responds better to lower frequencies. In addition, in mammals, the cochlea is coiled, which has been shown to enhance low-frequency vibrations as they travel through the fluid-filled coil. This spatial arrangement of sound reception is referred to as tonotopy. For very low frequencies (below 20 Hz), the waves propagate along the complete route of the cochlea – differentially up vestibular duct and tympanic duct all the way to the helicotrema.

Because of their structural specialization, Boettcher cells are believed to play a significant role in the function of the cochlea. They demonstrate high levels of calmodulin, and may be involved in mediating Ca2+ regulation and ion transport. Boettcher cells are named after German pathologist Arthur Boettcher (1831-1889). Nitric oxide synthase is detected abundantly in the cytoplasm of their interdigitations.

Perilymph is an extracellular fluid located within the inner ear. It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation in perilymph is sodium, with the values of sodium and potassium concentration in the perilymph being 138 mM and 6.9 mM, respectively.

The existence of otoacoustic emissions is interpreted as implying backward as well as forward traveling waves generated in the cochlea, as proposed by Shera and Guinan.Shera, C. A. and Guinan, J. J. Jr., 1999. Evoked otoacoustic emissions arise by two fundamentally different mechanisms: a taxonomy for mammalian OAEs. The Journal of the Acoustical Society of America, 105(2), pp. 782–798.

Amblyaudia is a deficit in binaural integration of environmental information entering the auditory system. It is a disorder related to brain organization and function rather than what is typically considered a “hearing loss” (damage to the cochlea). It may be genetic or developmentally acquired or both. When animals are temporarily deprived of hearing from an early age, profound changes occur in the brain.

It therefore travelled "backwards" around the cochlea but still gave useful hearing as the hair cells were still deflected in the same way. The round window is often used as an approach for cochlear implant surgery. It has also recently been used as a site to place middle ear implantable hearing aid transducers. This work has been publicised by Prof.

Specializing in computational linguistics, Dougherty has published several books and articles on the subject. In recent years, Dougherty has become interested in the study of biolinguistics, focusing on the role of the cochlea in the evolution of animal communication systems and naturalistic applications of information theory. Professor Dougherty has made numerous contributions to advancing the study of semiotics at New York University.

In mice, GDF10 mRNA is abundant in the brain, inner ear, uterus, prostate, neural tissues, blood vessels and adipose tissue with low expression in spleen and liver. It is also present in bone of both adults and neonatal mice. Human GDF10 mRNA is found in the cochlea and lung of foetuses, and in testis, retina, pineal gland, and other neural tissues of adults.

Scharf et al. (1997) concluded that OCB-mediated suppression of sounds in the cochlea was responsible for the suppression of unexpected sounds, and thus plays a role in selective attention in normal hearing. In contrast to Scharf's theory, Tan et al. (2008) argued that the OCB's role in selective listening pertains to the enhancement of a cued, or expected tone.

Aural atresia is the underdevelopment of the middle ear and canal and usually occurs in conjunction with microtia. Atresia occurs because patients with microtia may not have an external opening to the ear canal, though. However, the cochlea and other inner ear structures are usually present. The grade of microtia usually correlates to the degree of development of the middle ear.

The evolution of echolocation in bats. Trends in Ecology & Evolution, 21(3), 149–156. . The common features shared by bats with DSC are that they produce CF sounds, and that they have a specialized cochlea that is adapted to receiving a narrow range of frequencies with high resolution. DSC allows these bats to utilize these features to optimize the echolocation behavior.

Algorithm for extraction of pitch and pitch salience from complex tonal signals. Journal of the Acoustical Society of America, 71(3), 679-688. pitch perception can be divided into two separate stages: auditory spectral analysis and harmonic pitch pattern recognition. In the first stage, the inner ear (cochlea and basilar membrane) performs a running spectral analysis of the incoming signal.

In 2008 he was named chairman of the hospital for otorhinolaryngology. In 2013 he became dean for research affairs at the Paracelsus Private Medical University of Salzburg Austria. Rasp went abroad for advanced training: 1996 in Amsterdam (rhino-plasticity), 1998 in Zurich (base of skull surgery), 2000 in Miami (tympanic surgery and cochlea implantation) and 2004 in New Orleans (base of skull surgery).

Otoancorin is a protein found in the vertebrate inner ear, on the sensory epithelia where it connects to the gel matrix. Otoancorin is found in the cochlea, utricule, saccule, and under the cupulae on the surface of apical dells in the sensory epithelia. In humans the gene that encodes otoancorin is called OTOA. It is on chromosome 16p12.2 and contains 28 exons.

This gene is expressed in fetal cochlea and many other tissues, and is thought to be involved in the development and maintenance of the inner ear or the contents of the perilymph and endolymph. This gene was also identified as a tumor associated gene that is overexpressed in ovarian tumors. Four alternatively spliced variants have been described, two of which encode identical products.

Michel aplasia is thought to result from failure of development of the otic placode, due to developmental arrest at the third week of gestation. The common cavity deformity, a confluence of illdefined cochlea and vestibular organ results from a disruption during the fourth and fifth week. An arrest in fifth or sixth week of gestation result in cochlear aplasia or cochlear hypoplasia respectively.

Many sounds in everyday life, including speech and music, are broadband; the frequency components spread over a wide range and there is no well-defined way to represent the signal in terms of ENVp and TFSp. However, in a normally functioning cochlea, complex broadband signals are decomposed by the filtering on the basilar membrane (BM) within the cochlea into a series of narrowband signals. Therefore, the waveform at each place on the BM can be considered as an envelope (ENVBM) superimposed on a more rapidly oscillating carrier, the temporal fine structure (TFSBM). The ENVBM and TFSBM depend on the place along the BM. At the apical end, which is tuned to low (audio) frequencies, ENVBM and TFSBM vary relatively slowly with time, while at the basal end, which is tuned to high frequencies, both ENVBM and TFSBM vary more rapidly with time.

In 1961, Professor Donald D. Greenwood utilized experimental methods within the field of psychoacoustics to measure the frequency resolution between critical bands within the human cochlea and develop a function correlating the anatomic location of the inner ear hair cells and the frequencies at which they are stimulated (Greenwood 1961a,b). Georg von Békésy demonstrated physiologically that different frequencies of sound stimulated different regions of the cochlea (Wilson 2004). Based upon the findings of Békésy, Greenwood placed four students under the age of 29 with presumably healthy cochleas in isolation chambers and introduced pure tones within the range of audible frequencies (20-20,000 Hz). Upon application of each tone, he then introduced a second pure tone of the same frequency and then raised and lowered the frequency until it was sufficiently different from the original frequency to become audible (Greenwood 1961a).

The acoustic reflex (also known as the stapedius reflex, stapedial reflex, auditory reflex, middle-ear-muscle reflex (MEM reflex, MEMR), attenuation reflex, cochleostapedial reflex or intra-aural reflex) is an involuntary muscle contraction that occurs in the middle ear in response to loud sound stimuli or when the person starts to vocalize. When presented with an intense sound stimulus, the stapedius and tensor tympani muscles of the ossicles contract. The stapedius stiffens the ossicular chain by pulling the stapes (stirrup) of the middle ear away from the oval window of the cochlea and the tensor tympani muscle stiffens the ossicular chain by loading the tympanic membrane when it pulls the malleus (hammer) in toward the middle ear. The reflex decreases the transmission of vibrational energy to the cochlea, where it is converted into electrical impulses to be processed by the brain.

There are approximately between 15,000 and 16,000 of these hair cells in one ear. Outer hair cells have stereocilia projecting towards the tectorial membrane, which sits above the organ of Corti. Stereocilia respond to movement of the tectorial membrane when a sound causes vibration through the cochlea. When this occurs, the stereocilia separate and a channel is formed that allows chemical processes to take place.

In a 'normal' ear the auditory filter has a shape similar to the one shown below. This graph reflects the frequency selectivity and the tuning of the basilar membrane. The auditory filter of a "normal" cochlea The tuning of the basilar membrane is due to its mechanical structure. At the base of the basilar membrane it is narrow and stiff and is most responsive to high frequencies.

The forelegs are strong and paddle-like, while the hind legs have disappeared, leaving behind only vestigial bones visible in X-rays. The tail is autotomous without any regeneration. Due to sacrificing the development of its ear to permit it to dig more efficiently, the Mexican mole lizard has evolved to have its skin transmit vibrations to the cochlea. Wever, Ernest Glen; Gans, Carl (1972).

Sounds consist of waves of air molecules that vibrate at different frequencies. These waves travel to the basilar membrane in the cochlea of the inner ear. Different frequencies of sound will cause vibrations in different location of the basilar membrane. We are able to hear different pitches because each sound wave with a unique frequency is correlated to a different location along the basilar membrane.

When this boost occurs, an acoustic reflex mechanism triggers and acts as a defense against these sounds. This mechanism seeks to reduce the sound energy in the ear by dampening its transfer from eardrum to cochlea. It has been seen that this process can reduce sound waves by up to 50 decibels. Although this mechanism can decrease the sound energy, it does not negate the oscillatory pressure.

In it he supported the views of Hermann von Helmholtz, with some reservations. His last paper described the presence of the lagena in the platypus, which is also found in birds. He saw this organ as a link between the cochlea of higher and lower vertebrates. In the British Medical Journal of January 1880 he reported the preliminary results of an early hearing aid.

A DACI tries to provide an answer for people with hearing problems for which no solution exists today. People with some problems at the level of the cochlea can be helped with a hearing aid. A hearing aid will absorb the incoming sound from a microphone, and offer enhanced through the natural way. For larger reinforcements, this may cause problems with feedback and distortion.

An auditory brainstem implant (ABI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf, due to retrocochlear hearing impairment (due to illness or injury damaging the cochlea or auditory nerve, and so precluding the use of a cochlear implant). In Europe, ABIs have been used in children and adults, and in patients with neurofibromatosis type II.

In the auditory system, sound vibrations (mechanical energy) are transduced into electrical energy by hair cells in the inner ear. Sound vibrations from an object cause vibrations in air molecules, which in turn, vibrate the ear drum. The movement of the eardrum causes the bones of the middle ear (the ossicles) to vibrate. These vibrations then pass into the cochlea, the organ of hearing.

Within the cochlea, the hair cells on the sensory epithelium of the organ of Corti bend and cause movement of the basilar membrane. The membrane undulates in different sized waves according to the frequency of the sound. Hair cells are then able to convert this movement (mechanical energy) into electrical signals (graded receptor potentials) which travel along auditory nerves to hearing centres in the brain.Eatock, R. (2010).

300x300px Audition, the process of hearing sounds, is the first stage of perceiving speech. Articulators cause systematic changes in air pressure which travel as sound waves to the listener's ear. The sound waves then hit the listener's ear drum causing it to vibrate. The vibration of the ear drum is transmitted by the ossicles—three small bones of the middle ear—to the cochlea.

The inner ear of barn owls includes the vestibular organ, cochlea, and auditory nerve. The anatomy of the inner ear in barn owls was studied in an experiment where three owls were utilized and fixed at laboratories by the intravascular perfusion of 1% formaldehyde and 1.25% glutaraldehyde in a 0.1 phosphate buffer.Smith, C., Konishi, M., & Schuff, N. 1985. Structure of the Barn Owls (Tyto alba) Inner Ear.

Stephen Polyak (born Stjepan Lucian Poljak; December 13, 1889 – March 9, 1955)Stephen Polyak biography, researchgate.net; accessed February 5, 2017. was an American neuroanatomist and neurologist considered to be one of the most prominent neuroanatomists of the 20th century. Polyak studied the functional structure of the organs of sight and hearing, explaining the function of the retina and the cochlea, and visual and auditory pathways and centers.

The teeth are shed once (milk teeth) during the animal's lifetime or not at all, as is the case in cetaceans. Mammals have three bones in the middle ear and a cochlea in the inner ear. They are clothed in hair and their skin contains glands which secrete sweat. Some of these glands are specialized as mammary glands, producing milk to feed the young.

Wiener, F.(1947), "On the diffraction of a progressive wave by the human head". Journal of the Acoustical Society of America, 19, 143-146. As the organ of hearing, the cochlea consists of two membranes, Reissner’s and the basilar membrane. The basilar membrane moves to audio stimuli through the specific stimulus frequency matches the resonant frequency of a particular region of the basilar membrane.

The bony labyrinth, or osseous labyrinth, is the network of passages with bony walls lined with periosteum. The three major parts of the bony labyrinth are the vestibule of the ear, the semicircular canals, and the cochlea. The membranous labyrinth runs inside of the bony labyrinth, and creates three parallel fluid filled spaces. The two outer are filled with perilymph and the inner with endolymph.

The vestibular system is the region of the inner ear where the semicircular canals converge, close to the cochlea. The vestibular system works with the visual system to keep objects in view when the head is moved. Joint and muscle receptors are also important in maintaining balance. The brain receives, interprets, and processes the information from all these systems to create the sensation of balance.

In this situation, the hair cells become hyperpolarized and the nerve afferents are not excited. There are two different types of fluid that surround the hair cells of the inner ear. The endolymph is the fluid that surrounds the apical surfaces of hair cells. Potassium is the major cation in the endolymph and is thought to be responsible for carrying the receptor currents in the cochlea.

In vertebrates, the majority of neurons belong to the central nervous system, but some reside in peripheral ganglia, and many sensory neurons are situated in sensory organs such as the retina and cochlea. Axons may bundle into fascicles that make up the nerves in the peripheral nervous system (like strands of wire make up cables). Bundles of axons in the central nervous system are called tracts.

The endocochlear potential (EP; also called endolymphatic potential) is the positive voltage of 80-100mV seen in the cochlear endolymphatic spaces. Within the cochlea the EP varies in the magnitude all along its length. When a sound is presented, the endocochlear potential changes either positive or negative in the endolymph, depending on the stimulus. The change in the potential is called the summating potential.

The inner hair cells provide the main neural output of the cochlea. The outer hair cells, instead, mainly receive neural input from the brain, which influences their motility as part of the cochlea's mechanical pre-amplifier. The input to the OHC is from the olivary body via the medial olivocochlear bundle. The cochlear duct is almost as complex on its own as the ear itself.

The cochlear nuclear complex is the first integrative, or processing, stage in the auditory system. Information is brought to the nuclei from the ipsilateral cochlea via the cochlear nerve. Several tasks are performed in the cochlear nuclei. By distributing acoustic input to multiple types of principal cells, the auditory pathway is subdivided into parallel ascending pathways, which can simultaneously extract different types of information.

Both the peripheral process and the axon are myelinated. In humans, there are on average 30,000 nerve fibers within the cochlear nerve. The number of fibers varies significantly across species; the domestic cat, for example, has an average of 50,000 fibers. The peripheral axons of auditory nerve fibers form synaptic connections with the hair cells of the cochlea via ribbon synapses using the neurotransmitter glutamate.

Sonic hedgehog may play a role in mammalian hair cell regeneration. By modulating retinoblastoma protein activity in rat cochlea sonic hedgehog allows mature hair cells that normally cannot return to a proliferative state to divide and differentiate. Retinoblastoma proteins suppress cell growth by preventing cells from returning to the cell cycle thereby preventing proliferation. Inhibiting the activity of Rb seems to allow cells to divide.

Prestin is a protein that is critical to sensitive hearing in mammals. It is encoded by the SLC26A5 (solute carrier anion transporter family 26, member 5) gene. Prestin is the motor protein of the outer hair cells of the inner ear of the mammalian cochlea. It is highly expressed in the outer hair cells, and is not expressed in the nonmotile inner hair cells.

The hindlimbs keep the body over the pectoral limbs which are stabilized by the thumbs. Common vampire bats have good eyesight. They are able to distinguish different optical patterns and may use vision for long-range orientation. These bats also have well-developed senses of smell and hearing: the cochlea is highly sensitive to low-frequency acoustics, and the nasal passages are relatively large.

The auditory system is the sensory system for hearing in which the brain interprets information from the frequency of sound waves, yielding the perception of tones. Sound waves enter the ear through the auditory canal. These waves arrive at the eardrum where the properties of the waves are transduced into vibrations. The vibrations travel through the bones of the inner ear to the cochlea.

Long-term research has shown that mechanical flexibility of the electrode array is one of the key factors for preserving residual hearing. The smaller the force used to insert the electrode, the greater the chance of protecting the fragile structures within the cochlea. Today only lateral wall electrodes are used. Studies with preshaped (modiolus-hugging electrodes) have been proven to be not so effective.

The former detects high frequencies and the latter low frequencies. Because the cochlea is short, frogs use electrical tuning to extend their range of audible frequencies and help discriminate different sounds. This arrangement enables detection of the territorial and breeding calls of their conspecifics. In some species that inhabit arid regions, the sound of thunder or heavy rain may arouse them from a dormant state.

He achieved a breakthrough during a vacation at the beach; he conceptualised using a seashell to replicate the human cochlea, and grass blades (which were flexible at the tip and gradually increasing in stiffness) to represent electrodes. Clark showed that the electrode bundle had to be free-fitting, and the wires needed to be terminated with circumferential bands to reduce friction against the outer wall of the cochlea, and so make it easier to pass the required distance. The bands had to be wide enough to minimise the charge density of the electric current for safety, but narrow enough for localised stimulation of the nerve fibers for the place coding of frequency. In order to address issues about the safety of the device, Clark conducted experiments to show that there was a minimal risk of meningitis from a middle ear infection if a fibrous tissue sheath grew around the electrode bundle.

The Greenwood function correlates the position of the hair cells in the inner ear to the frequencies that stimulate their corresponding auditory neurons. Empirically derived in 1961 by Donald D. Greenwood, the relationship has shown to be constant throughout mammalian species when scaled to the appropriate cochlear spiral lengths and audible frequency ranges. Moreover, the Greenwood function provides the mathematical basis for cochlear implant surgical electrode array placement within the cochlea.

Wiley: New York. and it is now known that both the morphological structure of hair cell papillae and the ion channels that characterize hair cell membranes confer spectral tuning properties. Ca2+ dependent K+ channels are produced as splice variants of the cSlo gene,Rosenblatt, K.P., Z-P. Sun, S Heller and A.J. Hudspeth. 1997. Distribution of Ca2+-activated K+ channel isoforms along the tonotopic gradient of the chicken’s cochlea.

The round window is one of the two openings from the middle ear into the inner ear. It is sealed by the secondary tympanic membrane (round window membrane), which vibrates with opposite phase to vibrations entering the inner ear through the oval window. It allows fluid in the cochlea to move, which in turn ensures that hair cells of the basilar membrane will be stimulated and that audition will occur.

The inner ear is a small but very complex organ. The inner ear consists of the cochlea, which is a spiral-shaped, fluid-filled tube. It is divided lengthwise by the organ of Corti, which is the main organ of mechanical to neural transduction. Inside the organ of Corti is the basilar membrane, a structure that vibrates when waves from the middle ear propagate through the cochlear fluid – endolymph.

BMP signal derived from myocardium is also involved in endocardial differentiation during heart development. Inhibited BMP signal in zebrafish embryonic model caused strong reduction of endocardial differentiation, but only had little effect in myocardial development. In addition, Notch-Wnt-Bmp crosstalk is required for radial patterning during mouse cochlea development via antagonizing manner. Mutations in BMPs and their inhibitors are associated with a number of human disorders which affect the skeleton.

Currently it is believed that auditory fatigue and NIHL are related to excessive vibrations of the inner ear which may cause structural damages.Adelman, C., Perez, R., Nazarian, Y., Freeman, S., Weinberger, J., & Sohmer, H. (2010). Furosemide Administered Before Noise Exposure Can Protect the Ear. [Article]. Annals of Otology Rhinology and Laryngology, 119(5), 342-349.Ou HC, Bohne BA, Harding GW. Noise damage in the C57BL/CBA mouse cochlea.

Pristerodon were among the earliest land animals able to hear airborne sound as opposed to hearing via ground vibrations. A South African specimen studied with neutron tomography has shown evidence of an eardrum on its lower jaw with the implication that it was hearing impaired during the act of chewing. The specimen had a 3mm cavity for cochlea which transformed sound frequency ranges into nerve impulses sent on to the brain.

The basic MOC acoustic reflex. The auditory nerve responds to sound, sending a signal to the cochlear nucleus. Afferent nerve fibres cross the midline from the cochlear nucleus to the cell bodies of the MOCS (located near the MSOC), whose efferent fibres project back to the cochlea (red). In most mammals, the majority of the reflex is ipsilateral (shown as a thicker line), effectuated by the crossed MOCS.

This raises the possibility that the TM may be involved in the longitudinal propagation of energy in the intact cochlea. MIT research correlates the TM with the ability of the human ear to hear faint noises. The TM influences inner ear sensory cells by storing calcium ions. When calcium store is depleted by loud sounds or by the introduction of calcium chelators, the responses of the sensory cells decrease.

The promontory of the tympanic cavity, also known as the cochlear promontory is a rounded hollow prominence, formed by the projection outward of the first turn of the cochlea. It is placed between the oval window and the round window, and is furrowed on its surface by small grooves, for the lodgement of branches of the tympanic plexus. A minute spicule of bone frequently connects the promontory to the pyramidal eminence.

The toothed whales are also unusual in that the ears are separated from the skull and placed well apart, which assists them with localizing sounds, an important element for echolocation. Studies have found there to be two different types of cochlea in the dolphin population. Type I has been found in the Amazon river dolphin and harbour porpoises. These types of dolphin use extremely high frequency signals for echolocation.

Cochlin is a protein that in humans is encoded by the COCH gene. It is an extracellular matrix (ECM) protein highly abundant in the cochlea and vestibule of the inner ear, constituting the major non-collagen component of the ECM of the inner ear. The protein is highly conserved in human, mouse, and chicken, showing 94% and 79% amino acid identity of human to mouse and chicken sequences, respectively.

We can hear many more different tones than there are hair cells in the cochlea; pitch discrimination, without which a violin could not be played in tune, is a hyperacuity. Hyperacuity has been identified in many animal species, for example in the detection of prey by the electric fish, echolocation in the bat, and in the ability of rodents to localize objects based on mechanical deformations of their whiskers.

The reptilian nervous system contains the same basic part of the amphibian brain, but the reptile cerebrum and cerebellum are slightly larger. Most typical sense organs are well developed with certain exceptions, most notably the snake's lack of external ears (middle and inner ears are present). There are twelve pairs of cranial nerves. Due to their short cochlea, reptiles use electrical tuning to expand their range of audible frequencies.

In an 1856 paper he described what were to become known as the "cells of Claudius", which are cells located on the basilar membrane of the inner ear's cochlea. His name is also associated with "Claudius' fossa", now referred to as the ovarian fossa, a depression in the parietal peritoneum of the pelvis. In 1867 he published Das Gehörorgan von Rhytina stelleri ("The hearing organ of Rhytina stelleri ").

Furthermore, it has been demonstrated that patients with otitis media have more depression/anxiety-related disorders compared to individuals with normal hearing. Once the infections resolve and hearing thresholds return to normal, childhood otitis media may still cause minor and irreversible damage to the middle ear and cochlea. More research on the importance of screening all children under 4 years old for otitis media with effusion needs to be performed.

Primary auditory neurons carry action potentials from the cochlea into the transmission pathway shown in the adjacent image. Multiple relay stations act as integration and processing centers. The signals reach the first level of cortical processing at the primary auditory cortex (A1), in the superior temporal gyrus of the temporal lobe. Most areas up to and including A1 are tonotopically mapped (that is, frequencies are kept in an ordered arrangement).

Variations within the human genome are being studied to determine susceptibility to chronic diseases, as well as infectious diseases. According to Aileen Kenneson and Coleen Boyle, about one sixth of the U.S. population has some degree of hearing loss. Recent research has linked variants in the gap junction beta 2 (GJB2) gene to nonsyndromic prelingual sensorineural hearing loss. GJB2 is a gene encoding for connexin, a protein found in the cochlea.

Notably, the loss of tonotopicity generally occurs only for TFSn coding but not for ENVn coding, which is consistent with greater perceptual deficits in TFS processing. This tonotopic degradation is likely to have important implications for speech perception, and can account for degraded coding of vowels following noise- induced hearing loss in which most of the cochlea responds to only the first formant, eliminating the normal tonotopic representation of the second and third formants.

Cockayne syndrome results from a mutation in genes that interfere with transcription-coupled repair of nuclear and mitochondrial DNA, replication, and transcription. Neuronal death is predominantly in the cerebellum, but this disease also causes apoptosis in purkinje cells and causes them to have dystrophic dendrites. Loss of sensory receptors in the cochlea, vestibules, and retina result in ganglion degeneration and transneuronal degeneration. Demyelination also results as oligodendrocytes and Schwann cells are killed.

A bone anchored hearing aid (BAHA) is a surgically implanted auditory prosthetic based on bone conduction. It is an option for patients without external ear canals, when conventional hearing aids with a mold in the ear cannot be used. The BAHA uses the skull as a pathway for sound to travel to the inner ear. For people with conductive hearing loss, the BAHA bypasses the external auditory canal and middle ear, stimulating the functioning cochlea.

From there, the two channels are represented with a sequence of inductors and resistors for fluid flow within each channel with the two channels joined with a sequence of series resonant RLC circuits. Voltages across capacitances represent basilar membrane displacements. Element values along the cochlea are tapered in a logarithmic fashion to represent lowering frequency responses with distance. The pattern of voltages along the basilar membrane can be viewed on an oscilloscope.

The cochlear implant is a device surgically implanted in the skull that provides stimulation to the nerve to promote hearing. It is a prosthetic with wires attached to the cochlea and is located behind the ear. The cochlear implant has a microphone, connecting cables, a speech processor, and a battery. The processor converts sounds into electrical impulses by taking information from sound patterns and producing an electrical pulse in the ear of the host.

Therefore, in response to the electrical stimulations provided by the efferent nerve supply, they can alter in length, shape and stiffness. These changes influence the response of the basilar membrane to sound. It is therefore clear that the OHCs play a major role in the active processes of the cochlea. The main function of the active mechanism is to finely tune the basilar membrane, and provide it with a high sensitivity to quiet sounds.

Figure 4: Neural tuning curve for normal hearing. The traveling wave along the basilar membrane peaks at different places along it, depending on whether the sound is low or high frequency. Due to the mass and stiffness of the basilar membrane, low frequency waves peak in the apex, while high frequency sounds peak in the basal end of the cochlea. Therefore, each position along the basilar membrane is finely tuned to a particular frequency.

It is within these areas where motor activation, attention, executive function, and somatosensory (body) awareness is primarily mediated. Auditory entrainment (AE) is the same concept as visual entrainment, with the exception that auditory signals are passed from the cochlea of the ears into the thalamus via the medial geniculate nucleus, whereas visual entrainment passes from the retina into the thalamus via the lateral geniculate nucleus.McClintic, J. (1978). Physiology of the human body.

The lateral lemnisci (red) connects lower brainstem auditory nuclei to the inferior colliculus in the midbrain. The sound information from the cochlea travels via the auditory nerve to the cochlear nucleus in the brainstem. From there, the signals are projected to the inferior colliculus in the midbrain tectum. The inferior colliculus integrates auditory input with limited input from other parts of the brain and is involved in subconscious reflexes such as the auditory startle response.

Belemnites had a radula—the mouth—embedded in the buccal mass—the first part of a gastropod digestive system—similar to open ocean predatory cephalopods. The radula had rows of seven teeth, consistent with modern predatory squid. The statocysts—which give a sense of balance and function much like the cochlea of the ear—were large, much like in modern fast-moving squid. Like other cephalopods, the skin was likely thin and slippery.

The other toughening measure is to spread a given amount of energy to the system over a longer amount of time. This would allow recovery processes to take place during the quiet interludes that are gained by increasing the exposure duration. So far, studies have not shown a direct correlation between the amount of toughening and the amount of threshold shift experienced. This suggests that even a toughened cochlea may not be completely protected.

The damaged structure then produces the symptoms the patient presents with. Ototoxicity in the cochlea may cause hearing loss of the high-frequency pitch ranges or complete deafness, or losses at points between. It may present with bilaterally symmetrical symptoms, or asymmetrically, with one ear developing the condition after the other or not at all. The time frames for progress of the disease vary greatly and symptoms of hearing loss may be temporary or permanent.

Sound waves enter the ear via the ear canal and travel until they reach the tympanic membrane. The tympanic membrane then sends these waves through the ossicles of the middle ear and into the inner ear that includes the vestibular organ, cochlea, and auditory nerve. These species of owl are then able to use interaural time difference (ITD) and interaural level difference (ILD) to pinpoint the location and elevation of their prey.

At the beginning of 1850 Corti had received the invitation of the anatomist Albert Kölliker and had moved to Würzburg, where he made friends with Virchow. At the Kölliker Laboratory he began to work on the mammalian auditory system. Corti spent a short time in Utrecht, where he visited Professors Jacobus Schroeder van der Kolk and Pieter Harting. During his stay he learned to use methods to preserve several preparations of the cochlea.

As the middle ear is only a narrow space, the eardrum only has to retract a short distance before it touches boney structures within the middle ear such as the ossicles. It may become adherent to these bones and in some cases, this contact leads to erosion of the bone. As well as ossicular erosion, the bone of the ear canal (e.g. the scutum) and even bone over the cochlea (the promontory) can become eroded.

Both types of pillar cell have thousands of cross linked microtubules and actin filaments in parallel orientation. They provide mechanical coupling between the basement membrane and the mechanoreceptors on the hair cells. Boettcher's cells are found in the organ of Corti where they are present only in the lower turn of the cochlea. They lie on the basilar membrane beneath Claudius' cells and are organized in rows, the number of which varies between species.

The presence of cutamesine is positively correlated with the presence of hippocampal brain‐derived neurotrophic factor (BDNF). Due to the relationship between the presence of BDNF and ciliary neurotrophic factor and the preservation of auditory nerves, it is thought that cutamesine may have a positive effect on the health of the cochlea. Despite the apparent auditory benefits of cutamesine treatment, it does not prevent hearing loss that is a result of aging.

DSC is only found in CF bats. This is because they have a narrow range of frequencies to which they are optimally sensitive, and have a specialized cochlea that is adapted to responding to one frequency with high resolution. DSC however is not employed by frequency-modulated, or FM, bats. These bats have a broad range of frequencies to which they are maximally sensitive, and thus do not need to tightly modulate the echo frequency.

Closer to the front of the embryo, the vesicles differentiate into a rudimentary saccule, which will eventually become the saccule and cochlea. Part of the saccule will eventually give rise and connect to the cochlear duct. This duct appears approximately during the sixth week and connects to the saccule through the ductus reuniens. As the cochlear duct's mesenchyme begins to differentiate, three cavities are formed: the scala vestibuli, the scala tympani and the scala media.

Cochlea and vestibular system The semicircular ducts provide sensory input for experiences of rotary movements. They are oriented along the pitch, roll, and yaw axes. Each canal is filled with a fluid called endolymph and contains motion sensors within the fluids. At the base of each canal, the bony region of the canal is enlarged which opens into the utricle and has a dilated sac at one end called the osseous ampullae.

The walls of the hollow cochlea are made of bone, with a thin, delicate lining of epithelial tissue. This coiled tube is divided through most of its length by an inner membranous partition. Two fluid-filled outer spaces (ducts or scalae) are formed by this dividing membrane. At the top of the snailshell-like coiling tubes, there is a reversal of the direction of the fluid, thus changing the vestibular duct to the tympanic duct.

Inselberg held senior research positions at IBM where he developed a mathematical model of the ear (cochlea) (Time November 1974) and later collision-avoidance algorithms for air traffic control (3 USA patents). Concurrently he had joint appointments at UCLA, USC, Technion and Ben Gurion University. Since 1995 he has been a professor at the School of Mathematical Sciences of Tel Aviv University. He was elected senior fellow at the San Diego Supercomputing Center in 1996.

Hearing impairment is a heterogeneous condition with over 40 loci described. The protein encoded by this gene is expressed in fetal cochlea, however, its function is not known. Nonsyndromic hearing impairment is associated with a mutation in this gene. The observation that DFNA5 is epigenetically inactivated in a large number of cancers of frequent types (gastric, colorectal, and breast) is another important finding and is in line with its apoptosis-inducing properties.

Within the core (A1), its structure preserves tonotopy, the orderly representation of frequency, due to its ability to map low to high frequencies corresponding to the apex and base, respectively, of the cochlea. Data about the auditory cortex has been obtained through studies in rodents, cats, macaques, and other animals. In humans, the structure and function of the auditory cortex has been studied using functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and electrocorticography.

When the head is exposed to the water, some sound is transmitted by the eardrum and middle ear, but a significant part reaches the cochlea independently, by bone conduction. Some sound localisation is possible, though difficult. Human hearing underwater, in cases where the diver's ear is wet, is less sensitive than in air. Frequency sensitivity underwater also differs from that in air, with a consistently higher threshold of hearing underwater; sensitivity to higher frequency sounds is reduced the most.

Cobl knockout mice were viable and showed no obvious defects in neural tube closure and/or body laterality. Instead, Cobl knock out mice were reported to show defects in the inner ear suggesting a role of Cobl in postnatal planar cell polarity refinements and in the organization of the sensory structures in the cochlea. In line, Cobl KO mice showed defects in cochlear amplification. Zebra fish deficient for Cobl showed severe defects in body laterality and balance keeping.

He identified the cells' axon, which he called an "axis cylinder", and its dendrites, which he referred to as protoplasmic processes. He postulated that dendrites must fuse to form a continuous network. His name is lent to the "nucleus of Deiters", also called the lateral vestibular nucleus, and to "Deiters' cells", structures that are associated with outer hair cells in the cochlea of the inner ear. Deiters died in 1863 from typhoid fever at the age of 29.

Studies on zebra finch have shown that nuclei in the auditory thalamus, two steps up from the cochlea, do not passively relay input from peripheral sensory structures into higher forebrain structures. Thalamic nuclei show different patterns of gene expression in response to different stimuli, implicating them in the process of acoustic discrimination.Brauth, S.E., W. Liang and W.S. Hall. 2006. Contact-call driven and tone-driven zenk expression in the nucleus ovoidalis of the budgerigar (Melopsittacus undulates).

Sensory hearing loss is caused by abnormal structure or function of the hair cells of the organ of Corti in the cochlea. Neural hearing impairments are consequent upon damage to the eighth cranial nerve (the vestibulocochlear nerve) or the auditory tracts of the brainstem. If higher levels of the auditory tract are affected this is known as central deafness. Central deafness may present as sensorineural deafness but should be distinguishable from the history and audiological testing.

Damage to the cochlea can occur in several ways, for example by viral infection, exposure to ototoxic chemicals, and intense noise exposure. Damage to the OHCs results in either a less effective active mechanism, or it may not function at all. OHCs contribute to providing a high sensitivity to quiet sounds at a specific range of frequencies (approximately 2–4 kHz). Thus, damage to the OHCs results in the reduction of sensitivity of the basilar membrane to weak sounds.

Findings with the inner ear in Johanson–Blizzard syndrome give explanation to the presence of bilateral sensorineural hearing loss in most patients affected by the disorder. The formation of cystic tissue in both the cochlea and vestibule, with resulting dilation (widening) and malformation of these delicate structures has been implicated. Congenital deformations of the temporal bone and associated adverse anatomical effects on innervation and development of the inner ear also contribute to this type of hearing loss.

Forkhead box I1 is a protein that in humans is encoded by the FOXI1 gene. This gene belongs to the forkhead family of transcription factors which is characterized by a distinct forkhead domain. The specific function of this gene has not yet been determined; however, it is possible that this gene plays an important role in the development of the cochlea and vestibulum, as well as embryogenesis. wo transcript variants encoding different isoforms have been found for this gene.

The auditory brainstem response (ABR) test gives information about the inner ear (cochlea) and nerve pathways for hearing via ongoing electrical activity in the brain measured by electrodes placed on the scalp. Five different waves (I to V) are measured for each ear. Each waveform represents specific anatomical points along the auditory neural pathway. Delays of one side relative to the other suggest a lesion in cranial nerve VIII between the ear and brainstem or in the brainstem itself.

The basilar membrane is tonotopic, so that each frequency has a characteristic place of resonance along it. Characteristic frequencies are high at the basal entrance to the cochlea, and low at the apex. Basilar membrane motion causes depolarization of the hair cells, specialized auditory receptors located within the organ of Corti. While the hair cells do not produce action potentials themselves, they release neurotransmitter at synapses with the fibers of the auditory nerve, which does produce action potentials.

The data and power carrier are transmitted through a pair of coupled coils to the hermetically sealed internal unit. By extracting the power and demodulating the data, electric current commands are sent to the cochlea to stimulate the auditory nerve through microelectrodes. The key point is that the internal unit does not have a battery and it should be able to extract the required energy. Also to reduce the infection, data is transmitted wirelessly along with power.

226x226px Waardenburg syndrome type 2A (with a mutation in MITF) has been found in dogs, Fleckvieh cattle, minks, mice and a golden hamster. Degeneration of the cochlea and saccule, as seen in Waardenburg syndrome, has also been found in deaf white cats, Dalmatians and other dog breeds, white minks and mice. Domesticated cats with blue eyes and white coats are often completely deaf. Deafness is far more common in white cats than in those with other coat colors.

Ototoxicity is the property of being toxic to the ear (oto-), specifically the cochlea or auditory nerve and sometimes the vestibular system, for example, as a side effect of a drug. The effects of ototoxicity can be reversible and temporary, or irreversible and permanent. It has been recognized since the 19th century. There are many well-known ototoxic drugs used in clinical situations, and they are prescribed, despite the risk of hearing disorders, to very serious health conditions.

Mammalian cochlear hair cells are of two anatomically and functionally distinct types, known as outer, and inner hair cells. Damage to these hair cells results in decreased hearing sensitivity, and because the inner ear hair cells cannot regenerate, this damage is permanent. However, other organisms, such as the frequently studied zebrafish, and birds have hair cells that can regenerate. The human cochlea contains on the order of 3,500 inner hair cells and 12,000 outer hair cells at birth.

A temporal- bone CT using thin slices makes it possible to diagnose the degree of stenosis and atresia of the external auditory canal, the status of the middle ear cavity, the absent or dysplastic and rudimentary ossicles, or inner ear abnormalities such as a deficient cochlea. Two- and three-dimensional CT reconstructions with VRT and bone and skin-surfacing are helpful for more accurate staging and the three-dimensional planning of mandibular and external ear reconstructive surgery.

If two sounds of two different frequencies are played at the same time, two separate sounds can often be heard rather than a combination tone. The ability to hear frequencies separately is known as frequency resolution or frequency selectivity. When signals are perceived as a combination tone, they are said to reside in the same critical bandwidth. This effect is thought to occur due to filtering within the cochlea, the hearing organ in the inner ear.

Deiters' cells (phalangeal cells) are a type of neuroglial cell found in the organ of Corti and organised in one row of inner phalangeal cells and three rows of outer phalangeal cells. They are the supporting cells of the hair cell area within the cochlea. They are named after the German pathologist Otto Deiters (1834-1863) who described them. Hensen's cells are high columnar cells that are directly adjacent to the third row of Deiters’ cells.

The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the eardrum to the oval window of the cochlea. While the stapes is present in all tetrapods, the malleus and incus evolved from lower and upper jaw bones present in reptiles.

The outer ear receives sound, transmitted through the ossicles of the middle ear to the inner ear, where it is converted to a nervous signal in the cochlear and transmitted along the vestibulocochlear nerve. The inner ear sits within the temporal bone in a complex cavity called the bony labyrinth. A central area known as the vestibule contains two small fluid-filled recesses, the utricle and saccule. These connect to the semicircular canals and the cochlea.

The two muscles reflexively contract to dampen excessive vibrations. Vibration of the oval window causes vibration of the endolymph within the vestibule and the cochlea. The inner ear houses the apparatus necessary to change the vibrations transmitted from the outside world via the middle ear into signals passed along the vestibulocochlear nerve to the brain. The hollow channels of the inner ear are filled with liquid, and contain a sensory epithelium that is studded with hair cells.

Sometimes artificial ear bones are placed to substitute for damaged ones, or a disrupted ossicular chain is rebuilt in order to conduct sound effectively. Hearing aids or cochlear implants may be used if the hearing loss is severe or prolonged. Hearing aids work by amplifying the sound of the local environment and are best suited to conductive hearing loss. Cochlear implants transmit the sound that is heard as if it were a nervous signal, bypassing the cochlea.

The oval window (or fenestra vestibuli) is a membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the inner ear. The oval window is the intersection of the middle ear with the inner ear and is directly contacted by the stapes; by the time vibrations reach the oval window, they have been amplified over 10 timesMoore and Dalley. Clinically Oriented Anatomy.

Higher pressure is necessary at the oval window than at the typanic membrane because the inner ear beyond the oval window contains liquid rather than air. The stapedius reflex of the middle ear muscles helps protect the inner ear from damage by reducing the transmission of sound energy when the stapedius muscle is activated in response to sound. The middle ear still contains the sound information in wave form; it is converted to nerve impulses in the cochlea.

Afferent neurons innervate cochlear inner hair cells, at synapses where the neurotransmitter glutamate communicates signals from the hair cells to the dendrites of the primary auditory neurons. There are far fewer inner hair cells in the cochlea than afferent nerve fibers – many auditory nerve fibers innervate each hair cell. The neural dendrites belong to neurons of the auditory nerve, which in turn joins the vestibular nerve to form the vestibulocochlear nerve, or cranial nerve number VIII.Meddean – CN VIII.

This stiffness is due to, among other things, the thickness and width of the basilar membrane,Camhi, J. Neuroethology: nerve cells and the natural behavior of animals. Sinauer Associates, 1984. which along the length of the cochlea is stiffest nearest its beginning at the oval window, where the stapes introduces the vibrations coming from the eardrum. Since its stiffness is high there, it allows only high-frequency vibrations to move the basilar membrane, and thus the hair cells.

The cochlear nerve (also auditory or acoustic neuron) is one of two parts of the vestibulocochlear nerve, a cranial nerve present in amniotes, the other part being the vestibular nerve. The cochlear nerve carries auditory sensory information from the cochlea of the inner ear directly to the brain. The other portion of the vestibulocochlear nerve is the vestibular nerve, which carries spatial orientation information to the brain from the semicircular canals, also known as semicircular ducts.

Specifically, α1D subunits confer low-voltage activation and slowly inactivating Ca2+ currents, ideal for particular physiological functions such as neurotransmitter release in cochlea inner hair cells. The biophysical properties of Cav1.3 channels are closely regulated by a C-terminal modulatory domain (CTM), which affects both the voltage dependence of activation and Ca2+ dependent inactivation. Cav1.3 have a low affinity for DHP and activate at sub-threshold membrane potentials, making them ideal for a role in cardiac pacemaking.

Meanwhile, in front of the exoccopitals is an attachment for the opisthotic bone, which forms most of the side of the braincase. A small indentation between the opisthotic and exoccipital attachments may be the lagenar recess. This indentation likely held an organ of the inner ear known as the lagena, which in mammals develops into the spiral-shaped cochlea. Above the occipital condyle is the foramen magnum, a massive hole where the spinal cord exits the braincase.

The best understood mechanism is fixation of the stapes footplate to the oval window of the cochlea. This greatly impairs movement of the stapes and therefore transmission of sound into the inner ear ("ossicular coupling"). Additionally the cochlea's round window can also become sclerotic, and in a similar way impair movement of sound pressure waves through the inner ear ("acoustic coupling"). Conductive hearing loss is usually concomitant with impingement of abnormal bone on the stapes footplate.

The gain unit also performs the function of dynamic range compression, thereby compensating for the function of non-linear amplification of the human cochlea. The processed broadband signal is synthesized using a synthesis filter bank (SFB). AFB and SFB can be realised as DFT-modulated filter banks, which is one of the most popular filter bank type used in modern hearing aids. The output signal can be multiplied by the total gain, which provides a comfortable sound level.

However, at the apex the membrane is wide and flexible and is most responsive to low frequencies. Therefore, different sections of the basilar membrane vibrate depending on the frequency of the sound and give a maximum response at that particular frequency. In an impaired ear, however the auditory filter has a different shape compared to that of a 'normal' ear. The auditory filter of an impaired cochlea The auditory filter of an impaired ear is flatter and broader compared to a normal ear.

In the membrane of the outer hair cells there are motor proteins associated with the membrane. Those proteins are activated by sound-induced receptor potentials as the basilar membrane moves up and down. These motor proteins can amplify the movement, causing the basilar membrane to move a little bit more, amplifying the traveling wave. Consequently, the inner hair cells get more displacement of their cilia and move a little bit more and get more information than they would in a passive cochlea.

Large vocal pads can also lower the pitch, as in the low-pitched roars of big cats. The production of infrasound is possible in some mammals such as the African elephant (Loxodonta spp.) and baleen whales. Small mammals with small larynxes have the ability to produce ultrasound, which can be detected by modifications to the middle ear and cochlea. Ultrasound is inaudible to birds and reptiles, which might have been important during the Mesozoic, when birds and reptiles were the dominant predators.

The Greenwood function is species- dependent and has shown to be preserved in mammals when normalized to the species-dependent range of auditory frequencies and cochlear spiral length (Greenwood 1990). For humans, the recommended values for the constants are f=165.4(10^{2.1x}-0.88) (Greenwood 1990). According to Greenwood's paper, a = 2.1, if x is relative to the cochlea length, and a = 0.06 if x is calculated in mm. For individuals with sensorineural hearing loss surgical implantation of a cochlear implant is indicated.

The resulting effects of neurotoxicity include vertigo, numbness, tingling of the skin (paresthesia), muscle twitching, and seizures. Its toxic effect on the 8th cranial nerve causes ototoxicity, resulting in loss of balance and, more commonly, hearing loss. Damage to the cochlea, caused by the forced apoptosis of the hair cells, leads to the loss of high-frequency hearing and happens before any clinical hearing loss can be detected. Damage to the ear vestibules, most likely by creating excessive oxidative free radicals.

Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (cranial nerve VIII). SNHL accounts for about 90% of reported hearing loss. SNHL is usually permanent and can be mild, moderate, severe, profound, or total. Various other descriptors can be used depending on the shape of the audiogram, such as high frequency, low frequency, U-shaped, notched, peaked, or flat.

Auditory Neuropathy (AN) is a hearing disorder in which the outer hair cells of the cochlea are present and functional, but sound information is not transmitted sufficiently by the auditory nerve to the brain. Hearing loss with AN can range from normal hearing sensitivity to profound hearing loss. A neuropathy usually refers to a disease of the peripheral nerve or nerves, but the auditory nerve itself is not always affected in auditory neuropathy spectrum disorders. Prevalence in the population is relatively unknown.

There are two different systems associated with the mechanics of the cochlea: the classical passive system and an active process. The passive system works to stimulate the inner hair cells directly and works at levels above 40 dB. At stimulation levels that prevent the excitation of the passive system, prolonged noise exposure results in a decrease in the loudness heard over time, even when the actual intensity of the noise has not changed. This is caused by the exhaustion of the active process.

The active form of thyroxine, T3, has been found to be a potent inhibitor at nanomolar concentrations. Besides its role in lens biology, CRYM seems also to be involved in thyroid hormone signalling in other tissues. It could be demonstrated that CRYM mutations may cause deafness through thyroid hormone binding effects on the fibrocytes of the cochlea. Disruption of the CRYM gene leads to decreased T3 concentrations in both tissues and serum without alteration of peripheral T3 action in vivo.

214 Another way of dealing with distributed elements is to use a finite element analysis whereby the distributed element is approximated by a large number of small lumped elements. Just such an approach was used in one paper to model the cochlea of the human ear.Fukazawa & Tanaka, pp. 191-192 Another condition required of electrical systems for the application of the lumped element model is that no significant fields exist outside the component since these can couple to other unrelated components.

The first symptom in 90% of those with an acoustic neuroma is unexplained unilateral sensorineural hearing loss, meaning there is damage to the inner ear (cochlea) or nerve pathways from the inner ear to the brain. It involves a reduction in sound level, speech understanding and hearing clarity. In about 70 percent of cases there is a high frequency pattern of loss. The loss of hearing is usually subtle and worsens slowly, although occasionally a sudden loss of hearing may occur (i.e.

The olivocochlear bundle (OCB) originates in the superior olivary complex in the brainstem. The vestibulocochlear anastomosis carries the efferent axons into the cochlea, where they innervate the organ of Corti (OC). The OCB contains fibres projecting to both the ipsilateral and contralateral cochleae, prompting an initial division into crossed (COCB) and uncrossed (UCOCB) systems. More recently, however, the division of the OCB is based on the cell bodies’ site of origin in the brainstem relative to the medial superior olive (MSO).

The tympanic membrane (also known as the eardrum) may be perforated by the intensity of the pressure waves. Furthermore, the hair cells, the sound receptors found within the cochlea, can be permanently damaged and can result in a hearing loss of a mild to profound degree. Additionally, the intensity of the pressure changes from the blast can cause injury to the blood vessels and neural pathways within the auditory system. Therefore, affected individuals can have auditory processing deficits while having normal hearing thresholds.

Some patients will develop nasal congestion while others may experience rhinitis or a runny nose. Some patients adjust to the treatment within a few weeks, others struggle for longer periods, and some discontinue treatment entirely. However, studies show that cognitive behavioral therapy at the beginning of therapy dramatically increases adherence—by up to 148%. While common PAP side effects are merely nuisances, serious side effects such as eustachian tube infection, or pressure build-up behind the cochlea are very uncommon.

Bastian localized the auditory word center to the posterior MTG (middle temporal gyrus). Other opponents to the Wernicke-Lichtheim model were Sigmund Freud and Carl Freund. Freud (1891) suspected that the auditory deficits in aphasic patients was due to a secondary lesion to cochlea. This assertion was confirmed by Freund (1895), who reported two auditory agnosia patients with cochlear damage (although in a later autopsy, Freund reported also the presence of a tumor in the left STG in one of these patients).

Birds with eyes on the sides of their heads have a wide visual field, while birds with eyes on the front of their heads, such as owls, have binocular vision and can estimate the depth of field. The avian ear lacks external pinnae but is covered by feathers, although in some birds, such as the Asio, Bubo and Otus owls, these feathers form tufts which resemble ears. The inner ear has a cochlea, but it is not spiral as in mammals.

Jeffress' model proposes that two signals even from an asynchronous arrival of sound in the cochlea of each ear will converge synchronously on a coincidence detector in the auditory cortex based on the magnitude of the ITD (Fig. 2). Therefore, the ITD should correspond to an anatomical map that can be found within the brain. Masakazu Konishi's study on barn owls shows that this is true. Sensory information from the hair cells of the ears travels to the ipsilateral nucleus magnocellularis.

Zweig later turned to hearing research and neurobiology, and studied the transduction of sound into nerve impulses in the cochlea of the human ear, and how the brain maps sound onto the spatial dimensions of the cerebral cortex. In 1975, while studying the ear,, he discovered a version of the continuous wavelet transform, the cochlear transform. In 2003, Zweig joined the quantitative hedge fund Renaissance Technologies, founded by the former Cold War code breaker James Simons. He left the firm in 2010.

The stapes transmits these vibrations to the inner ear by pushing on the membrane covering the oval window, which separates the middle and inner ear. The inner ear contains the cochlea, the liquid-filled structure containing the hair cells. These cells serve to transform the incoming vibration to electrical signals, which can then be transmitted to the brain. The auditory nerve carries the signal generated by the hair cells away from the inner ear and towards the auditory receiving area in the cortex.

While it is ok if these levels go low in the average person, if they go low while taking deferiprone (Ferriprox) it can cause life- threatening infections that can result in death. Alleviation of the most common symptom, hearing loss, has been varyingly successful through the use of cochlear implants. Most people do not notice a large improvement after successful implantation, which is most likely due to damage to the vestibulocochlear nerve (cranial nerve VIII) and not the cochlea itself.Sydlowski, S.A. et al.

IGF-1 has an involvement in regulating neural development including neurogenesis, myelination, synaptogenesis, and dendritic branching and neuroprotection after neuronal damage. Increased serum levels of IGF-I in children have been associated with higher IQ. IGF-1 shapes the development of the cochlea through controlling apoptosis. Its deficit can cause hearing loss. Serum level of it also underlies a correlation between short height and reduced hearing abilities particularly around 3–5 years of age, and at age 18 (late puberty).

Moore and colleagues developed the Threshold Equalizing Noise (TEN) test for diagnosing dead regions in the cochlea; these are regions with very few or no functioning inner hair cells, synapses or neurons. The outcomes of the TEN test are relevant to the fitting of hearing aids and cochlear implants. The TEN test has been incorporated in the audiometers of several major manufacturers. Brian Moore also contributed to the development of tests for assessing monaural and binaural sensitivity to the temporal fine structure of sounds.

Frequency is developing a form of regenerative medicine pioneered by Langer and Karp in which novel small molecules activate dormant progenitor cells within the body, enabling the restoration of function to damaged tissues. Frequency’s first therapeutic target is chronic, noise-induced hearing loss, in which the hair cells within the cochlea are damaged and die, leading to hearing loss. Frequency’s experimental treatment, FX-322, underwent a Phase 1 first-in-human safety trial in Australia in 2017. The company announced the trial had met all endpoints.

Unlike models based on a series of active filters or represented with digital equations, an analog ear can incorporate nonlinearities that represent nonlinear actions of the basilar membrane, perhaps caused by asymmetric motions of sensory cells resulting in asymmetric motions of the basilar membrane. Difference frequencies could be generated as are observed in the human. Some difference frequencies originating in the cochlea can be observed in the outer ear. Neural signals responding to motions of the basilar membrane show responses in one direction as in rectification.

This vaguely imitates biological learning that integrates various preprocessors (cochlea, retina, etc.) and cortexes (auditory, visual, etc.) and their various regions. Its deep learning capability is further enhanced by using inhibition, correlation and by its ability to cope with incomplete data, or "lost" neurons or layers even amidst a task. It is fully transparent due to its link weights. The link-weights allow dynamic determination of innovation and redundancy, and facilitate the ranking of layers, of filters or of individual neurons relative to a task.

Drummer Andreas Schipflinger is a research and development technician in the construction of cochlea implant system hearing aids. Bassist Fabio D'Amore is a sound engineer and studio manager, as well as a teacher for both the bass and music theory. He also fronts the metal band Mirrormaze, and has performed on tours with Xandria. Former members Mario Hirzinger and Simon Holzknecht work as a nurse in a kidney dialysis center and a research and development technician in the optical and crystal manufacturing industry respectively.

Early work pertained to elucidating the properties and modeling of the acoustic reflex and some excursions into psychophysics. By 1965 he established the Auditory Physiology Laboratory where he and some seventy doctoral students, postdocs and colleagues have produced a body of work that can be characterized in various categories. [2.1] Contemporary interpretation of the origin and properties of gross electrical responses of the cochlea and auditory nerve. This work forms the basis of present-day measurements and understanding of compound electrical responses of the auditory periphery.

This information is then received by the cochlear implant's internal components. The receiver stimulator delivers the correct amount of electrical stimulation to the appropriate electrodes on the array to represent the sound signal that was detected. The electrode array stimulates the remaining auditory nerve fibers in the cochlea, which carry the signal on to the brain, where it is processed. One way to measure the developmental status and limits of plasticity of the auditory cortical pathways is to study the latency of cortical auditory evoked potentials (CAEP).

In normal hearing, the majority of the auditory signals that reach the organ of Corti in the first place come from the outer ear. Sound waves enter through the auditory canal and vibrate the tympanic membrane, also known as the eardrum, which vibrates three small bones called the ossicles. As a result, the attached oval window moves and causes movement of the round window, which leads to displacement of the cochlear fluid. However, the stimulation can happen also via direct vibration of the cochlea from the skull.

Horseshoe bats have sophisticated senses of hearing due to their well-developed cochlea, and are able to detect Doppler-shifted echoes. This allows them to produce and receive sounds simultaneously. Within horseshoe bats, there is a negative relationship between ear length and echolocation frequency: Species with higher echolocation frequencies tend to have shorter ear lengths. During echolocation, the ears can move independently of each other in a "flickering" motion characteristic of the family, while the head simultaneously moves up and down or side to side.

The saccule, or sacculus, is the smaller of the two vestibular sacs. It is globular in form and lies in the recessus sphæricus near the opening of the vestibular duct of the cochlea. Its cavity does not directly communicate with that of the utricle. The anterior part of the saccule exhibits an oval thickening, the macula acustica sacculi, or macula, to which are distributed the saccular filaments of the vestibular branch of the vestibulocochlear nerve, also known as the statoacoustic nerve or cranial nerve VIII.

The axons of the auditory nerve originate from the hair cells of the cochlea in the inner ear. Different sound frequencies are encoded by different fibers of the auditory nerve, arranged along the length of the auditory nerve, but codes for the timing and level of the sound are not segregated within the auditory nerve. Instead, the ITD is encoded by phase locking, i.e. firing at or near a particular phase angle of the sinusoidal stimulus sound wave, and the IID is encoded by spike rate.

A 2005 study achieved successful regrowth of cochlea cells in guinea pigs. However, the regrowth of cochlear hair cells does not imply the restoration of hearing sensitivity, as the sensory cells may or may not make connections with neurons that carry the signals from hair cells to the brain. A 2008 study has shown that gene therapy targeting Atoh1 can cause hair cell growth and attract neuronal processes in embryonic mice. Some hope that a similar treatment will one day ameliorate hearing loss in humans.

Some patients with autosomal recessive dRTA also have sensorineural hearing loss. Inheritance of this type of RTA results from either mutations to V-ATPase subunit isoform B1 or isoform a4 or mutations of band 3 (also called AE1), a Cl-/HCO3- exchanger. Twelve different mutations to V-ATPase isoform B1 and twenty-four different mutations in a4 lead to dRTA. Reverse transcription polymerase chain reaction studies have shown expression of the a4 subunit in the intercalated cell of the kidney and in the cochlea.

The vestibular system of the inner ear is responsible for the sensations of balance and motion. It uses the same kinds of fluids and detection cells (hair cells) as the cochlea uses, and sends information to the brain about the attitude, rotation, and linear motion of the head. The type of motion or attitude detected by a hair cell depends on its associated mechanical structures, such as the curved tube of a semicircular canal or the calcium carbonate crystals (otolith) of the saccule and utricle.

Section through the spiral organ of Corti, magnified. The stereocilia are the "hairs" sticking out of the tops of the inner and outer 442x442pxAs acoustic sensors in mammals, stereocilia are lined up in the organ of Corti within the cochlea of the inner ear. In hearing, stereocilia transform the mechanical energy of sound waves into electrical signals for the hair cells, which ultimately leads to an excitation of the auditory nerve. Stereocilia are composed of cytoplasm with embedded bundles of cross-linked actin filaments.

This centre sends descending projections to lower motor neurones of the limbs. In slightly more detail this corresponds to ear (cochlea) → cranial nerve VIII (auditory) → cochlear nucleus (ventral/inferior) → LLN → caudal pontine reticular nucleus (PnC). The whole process has a less than 10ms latency. There is no involvement of the superior/rostral or inferior/caudal colliculus in the reaction that "twitches" the hindlimbs, but these may be important for adjustment of pinnae and gaze towards the direction of the sound, or for the associated blink.

The upper portion of the spiral ligament (which forms the outer wall of the cochlear duct) contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. It produces endolymph for the scala media, one of the three fluid-filled compartments of the cochlea. The stria is a somewhat stratified epithelium containing primarily three cell types (marginal, intermediate, and basal cells) and intraepithelial capillaries. The marginal cells are involved primarily in K+ transport and line the endolymphatic space of the scala media.

With the movement of the basilar membrane, a shear force is created and a small potential is generated due to a difference in potential between the endolymph (scala media- +80 mV) and the perilymph (vestibular and tympanic ducts- -70 mV). EP is highest in the basal turn of the Cochlea and decreases in the magnitude towards the apex. EP is highly dependent on the metabolism and ionic transport. An acoustic stimulus produces a simultaneous change in conductance at the membrane of the receptor cell.

Besides the motor proteins above, there are many more types of proteins capable of generating forces and torque in the cell. Many of these molecular motors are ubiquitous in both prokaryotic and eukaryotic cells, although some, such as those involved with cytoskeletal elements or chromatin, are unique to eukaryotes. The motor protein prestin, expressed in mammalian cochlear outer hair cells, produces mechanical amplification in the cochlea. It is a direct voltage-to- force converter, which operates at the microsecond rate and possesses piezoelectric properties.

Ideas related to the frequency theory of hearing came about in the late 1800s as a result of the research of many individuals. In 1865, Heinrich Adolf Rinne challenged the place theory; he claimed that it’s not very efficient for complex sounds to be broken into simple sounds then be reconstructed in the brain. Later, Friedrich Voltolini added on by proposing that every auditory hair cell is stimulated by any sound. Correspondingly, William Rutherford provided evidence that this hypothesis was true, allowing greater accuracy of the cochlea.

In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear, and then to the oval window in the fluid-filled cochlea. Hence, it ultimately converts and amplifies vibration in air to vibration in fluid. The malleus bone bridges the gap between the eardrum and the other ossicles.

Their hearing can be measured at the round window as cochlear microphonics and summating potential (of the cochlea), and compound action potential and single-fibre responses (of the auditory nerve). These indicate a best hearing range near 1000 Hz. Earlier reports that their hearing sensitivity varied with the season have been shown to be an artefact of the seasonally varying sensitivity to anesthetics. Single-unit recordings from the auditory nerve show both spontaneous and nonspontaneous responses. Tuning curves show peak sensitivity between 200 Hz and 4.5 kHz.

There are many drugs currently on the market that are used to manipulate or treat sensory system disorders. For instance, Gabapentin is a drug that is used to treat neuropathic pain by interacting with one of the voltage-dependent calcium channels present on non-receptive neurons. Some drugs may be used to combat other health problems, but can have unintended side effects on the sensory system. Ototoxic drugs are drugs which affect the cochlea through the use of a toxin like aminoglycoside antibiotics, which poison hair cells.

The biochemical properties and channel permeabilities of these more complex channels differ from homotypic Cx30 or Cx26 channels. Overexpression of Cx30 in Cx30 null mice restored Cx26 expression and normal gap junction channel functioning and calcium signaling, but it is described that Cx26 expression is altered in Cx30 null mice. The researchers hypothesized that co-regulation of Cx26 and Cx30 is dependent on phospholipase C signaling and the NF-κB pathway. The cochlea contains two cell types, auditory hair cells for mechanotransduction and supporting cells.

There is no direct treatment for the patients with Waardenburg Syndrome Type 1, however, there are multiple ways in which the symptoms are managed. There are some options for hearing loss aid depending on the type faced by the patient. In previous cases, cochlea implants were successful to aid the hearing loss. There is also some genetic screening available that can assess whether children can inherit the mutation in the PAX3 gene, but not an overall prediction on the manifestation of the disease in the future generations.

The implant has two main components. The outside component is generally worn behind the ear, but could also be attached to clothing, for example, in young children. This component, the sound processor, contains microphones, electronics that include Digital Signal Processor chips, battery, and a coil which transmits a signal to the implant across the skin. The inside component, the actual implant, has a coil to receive signals, electronics, and an array of electrodes which is placed into the cochlea, which stimulate the cochlear nerve.

However, the role that lateral inhibition plays in auditory sensation is unclear. Some scientists found that lateral inhibition could play a role in sharpening spatial input patterns and temporal changes in sensation, others propose it plays an important role in processing low or high tones. Lateral inhibition is also thought to play a role in suppressing tinnitus. Tinnitus can occur when damage to the cochlea creates a greater reduction of inhibition than excitation, allowing neurons to become aware of sound without sound actually reaching the ear.

OAEs are considered to be related to the amplification function of the cochlea. In the absence of external stimulation, the activity of the cochlear amplifier increases, leading to the production of sound. Several lines of evidence suggest that, in mammals, outer hair cells are the elements that enhance cochlear sensitivity and frequency selectivity and hence act as the energy sources for amplification. One theory is that they act to increase the discriminability of signal variations in continuous noise by lowering the masking effect of its cochlear amplification.

In the anatomy of the human ear, the perilymphatic duct is where the perilymphatic space (vestibule of the ear) is connected to the subarachnoid space. This works as a type of shunt to eliminate excess perilymph fluid from the perilymphatic space around the cochlea of the ear. Perilymph is continuous with cerebrospinal fluid (CSF) in the subarachnoid space. CSF pressure abnormalities do not generally have clinical impact on the inner ear which is explained physically by the bore diameter and length of the perilymphatic duct.

There is a common misconception that all odd-eyed cats are born deaf in one ear. This is not true, as about 60%–70% of odd-eyed cats can hear. About 10%–20% of normal-eyed cats are born deaf or become deaf as part of the feline aging process. White cats with one or two blue eyes do, however, have a higher incidence of genetic deafness, with the white gene occasionally causing the degeneration of the cochlea, beginning a few days after birth.

Another successful visual-to-auditory sensory substitution device is the Prosthesis Substituting Vision for Audition (PSVA). This system utilizes a head-mounted TV camera that allows real-time, online translation of visual patterns into sound. While the patient moves around, the device captures visual frames at a high frequency and generates the corresponding complex sounds that allow recognition. Visual stimuli are transduced into auditory stimuli with the use of a system that uses pixel to frequency relationship and couples a rough model of the human retina with an inverse model of the cochlea.

By studying the embryos of birds and farm animals, he was able to determine individual stages involving the formation of the inner ears' labyrinth. From this research he was therefore able to conceptualize formation of the labyrinth in humans. Today, his name is lent to Reissner's membrane, a membrane inside the cochlea of the inner ear. Another anatomical structure that is named after him is Reissner's fiber, a long, fibrous aggregation of glycoproteins secreted by the subcommissural organ in the third ventricle and extending through the central canal of the spinal cord.

Once in the middle ear, which consists of the malleus, the incus, and the stapes; the sounds are changed into mechanical energy. After being converted into mechanical energy, the message reaches the oval window, which is the beginning of the inner ear. Once inside the inner ear, the message is transferred into hydraulic energy by going through the cochlea, which is filled with fluid, and on to the Organ of Corti. This organ again helps the sound to be transferred into a neural impulse that stimulates the auditory pathway and reaches the brain.

The bat echolocates at a very low frequency, with the calls being at a mean of 78.33 kHz, with a range of 62.96-82.96 kHz. The species' calls have a comparatively short CF component and a longer tampering FM component, suggesting that the bat uses these to hunt insects in narrow spaces. This can also be explained considering that the bats roost in deep recesses with narrow openings. The cochlea of this bat is at an intermediate state between that of non-specialized bats and long-constant- frequency bats.

Acoustic resonance is also important for hearing. For example, resonance of a stiff structural element, called the basilar membrane within the cochlea of the inner ear allows hair cells on the membrane to detect sound. (For mammals the membrane has tapering resonances across its length so that high frequencies are concentrated on one end and low frequencies on the other.) Like mechanical resonance, acoustic resonance can result in catastrophic failure of the vibrator. The classic example of this is breaking a wine glass with sound at the precise resonant frequency of the glass.

For people with unilateral hearing loss, the BAHA uses the skull to conduct the sound from the deaf side to the side with the functioning cochlea. Individuals under the age of two (five in the USA) typically wear the BAHA device on a Softband. This can be worn from the age of one month as babies tend to tolerate this arrangement very well. When the child's skull bone is sufficiently thick, a titanium "post" can be surgically embedded into the skull with a small abutment exposed outside the skin.

This reduction in the area of force application allows a large enough increase in pressure to transfer most of the sound energy into the liquid. The increased pressure will compress the fluid found in the cochlea and transmit the stimulus. Thus, the lever action of the ossicles changes the vibrations so as to improve the transfer and reception of sound, and is a form of impedance matching. However, the extent of the movements of the ossicles is controlled (and constricted) by two muscles attached to them (the tensor tympani and the stapedius).

Cochlearia have been found in a number of Roman sites from the 4th and 5th centuries AD, including the ThetfordBritish Museum retrieved 27 June 2010 and Hoxne Hoards. The word cochlea literally means spiral or snail shell, leading many to conclude that the spoon was designed so that the handle could be used to extract snails or cockles out of the shell. The Roman terms cochlearium, cochlear, and cochleare denote a liquid measure of a spoonful. A cochlearium was also a place where snails could be bred for eating.

Such pharmaceutical treatments as are employed are palliative rather than curative, and addressed to the underlying cause if one can be identified, in order to avert progressive damage. Profound or total hearing loss may be amenable to management by cochlear implants, which stimulate cochlear nerve endings directly. A cochlear implant is surgical implantation of a battery powered electronic medical device in the inner ear. Unlike hearing aids, which make sounds louder, cochlear implants do the work of damaged parts of the inner ear (cochlea) to provide sound signals to the brain.

Adelobasileus is a genus of mammal-like cynodont from the Late Triassic (Carnian), about 225 million years ago. It is known only from a partial skull recovered from the Tecovas Formation in the Palo Duro Canyon of western Texas, southern United States, referred to the species Adelobasileus cromptoni. Roughly contemporary with the mammaliaform Tikitherium, Adelobasileus predates the non-mammalian cynodonts Tritylodontidae and Tritheledontidae by 10 million years. In fact, distinct cranial features, especially the housing of the cochlea, suggest that Adelobasileus is a transitional form in the character transformation from cynodonts to Triassic mammals.

The vestibular system is composed of inner ear organs forming the "labyrinth": the semicircular canals, the otoliths, and the cochlea. The section below is an overview of the vestibular system, as it is crucial to the understanding of the righting reflex. Sensory information from the vestibular system allows the head to move back into position when disturbed as the rest of the body follows. The semicircular canals (brown, see figure) are arranged at angles to the horizontal plane of the head when it is in its normal vertical posture.

This spatial arrangement of sounds and their respective frequencies being processed in the basilar membrane is known as tonotopy. When the hair cells on the basilar membrane move back and forth due to the vibrating sound waves, they release neurotransmitters and cause action potentials to occur down the auditory nerve. The auditory nerve then leads to several layers of synapses at numerous clusters of neurons, or nuclei, in the auditory brainstem. These nuclei are also tonotopically organized, and the process of achieving this tonotopy after the cochlea is not well understood.

The middle ear consists of a small air-filled chamber that is located medial to the eardrum. Within this chamber are the three smallest bones in the body, known collectively as the ossicles which include the malleus, incus, and stapes (also known as the hammer, anvil, and stirrup, respectively). They aid in the transmission of the vibrations from the eardrum into the inner ear, the cochlea. The purpose of the middle ear ossicles is to overcome the impedance mismatch between air waves and cochlear waves, by providing impedance matching.

Speech perception can be corrected prior to language acquisition with cochlear implants. After a year and a half experience, researchers found the deaf culture was able to identify words and comprehend movements of others' lips. There is a greater opportunity to hear a sound depending on the location of electrodes compared to the tissue and the number of remaining neurons located in the auditory system. In addition, individual capacities as well as the neural supply to the cochlea play a role in the process of learning with cochlear implantation.

Merle to merle mating is currently only forbidden in three breeds. Recent research indicates that the majority of health issues occur in dogs carrying both piebald and merle genes. The suppression of pigment cells (melanocytes) in the iris and in the stria vascularis of the cochlea (inner ear) leads to blue eyes and deafness. An auditory-pigmentation disorder in humans, Waardenberg syndrome, reflects some of the problems associated with heterozygous and homozygous merle dogs and genetic research in dogs has been undertaken with the goal of better understanding the genetic basis of this human condition.

Endolymph has a high positive potential (80–120 mV in the cochlea), relative to other nearby fluids such as perilymph, due to its high concentration of positively charged ions. It is mainly this electrical potential difference that allows potassium ions to flow into the hair cells during mechanical stimulation of the hair bundle. Because the hair cells are at a negative potential of about -50 mV, the potential difference from endolymph to hair cell is on the order of 150 mV, which is the largest electrical potential difference found in the body.

The surviving heterozygous Ts exhibit great variations of shortened, kinked and otherwise malformed tails. They also weigh less than their wild-type littermates but have otherwise a normal life span. Additionally, Ts mice develop a conductive hearing loss shortly after the onset of hearing at around 3–4 weeks of age. The hearing loss is the result of ectopic ossification along the round window ridge at the outside of the cochlea, massive deposition of cholesterol crystals in the middle ear cavity, an enlarged Eustachian tube and a chronic otitis media with effusion.

The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential. Transduction occurs through vibrations of structures in the inner ear causing displacement of cochlear fluid and movement of hair cells at the organ of Corti to produce electrochemical signals.The Ear Pujol, R., Irving, S., 2013 Italian anatomist Alfonso Giacomo Gaspare Corti (1822–1876) discovered the organ of Corti in 1851.

Image showing the outer ear, middle ear, and inner ear, and how sound is conducted through the outer ear, to the ossicles of the middle ear, through to the inner ear and the cochlea, where the organ of Corti sits. The function of the organ of Corti is to change (transduce) auditory signals and minimise the hair cells' extraction of sound energy. It is the auricle and middle ear that act as mechanical transformers and amplifiers so that the sound waves end up with amplitudes 22 times greater than when they entered the ear.

Restoration The hypothetical last common ancestor of archosaurs is thought to have shared many features with Erythrosuchus, many of which are found in the braincase. For example, the inner part of the otic capsule (the skeletal structure surrounding the inner ear) is not entirely ossified, or completely formed of bone. Neither is the channel for the perilymphatic duct, which is a tube that leaves the lagena. The lagena is the portion of the inner ear responsible for hearing, and is known as the cochlea in mammals (although in mammals it is coiled rather than straight).

The Merkel nerve endings (also known as Merkel discs) detect sustained pressure. The lamellar corpuscles (also known as Pacinian corpuscles) in the skin and fascia detect rapid vibrations (of about 200–300 Hz). Receptors in hair follicles called hair root plexuses sense when a hair changes position. Indeed, the most sensitive mechanoreceptors in humans are the hair cells in the cochlea of the inner ear (no relation to the follicular receptors – they are named for the hair-like mechanosensory stereocilia they possess); these receptors transduce sound for the brain.

Neural pathway of vestibular/balance system The vestibular system, in vertebrates, is part of the inner ear. In most mammals, it is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals. As movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canals, which indicate rotational movements; and the otoliths, which indicate linear accelerations.

The steeper the incline, the greater the risk of the user slipping from the top of the screw. No doubt the reverse water wheel was easier to use with a horizontal treading surface. On the other hand, the screw could be operated by a crank handle fitted to the central axle, but would be more tiring since the weight of the operator does not bear on the crank, as it does when trod from above. Like the reverse water wheel, the cochlea was used for many other purposes apart from draining mines.

It damages the cochlea with lesions and degrades central portions of the auditory system. For some ototoxic chemical exposures, particularly styrene, the risk of hearing loss can be higher than being exposed to noise alone. The effects is greatest when the combined exposure include impulse noise. A 2018 informational bulletin by the US Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) introduces the issue, provides examples of ototoxic chemicals, lists the industries and occupations at risk and provides prevention information.

Sounds such as speech are decomposed by the peripheral auditory system of humans (the cochlea) into narrow frequency bands. The resulting signals convey information at different time scales to more central auditory structures. A dichotomy between slow "temporal envelope" cues and faster "temporal fine structure" (TFS) cues has been proposed to explore several aspects of auditory perception including speech intelligibility in quiet or against competing sound sources. Starting from the late nineties, Lorenzi conducted a research program on auditory perception combining signal processing, psychophysical, electrophysiological and computational methods based on this envelope/TFS dichotomy.

Studies involving rapidly changing scenes show the percept derives from numerous processes that involve time delays.see Moutoussis and Zeki (1997) Recent fMRI studies show that dreams, imaginings and perceptions of things such as faces are accompanied by activity in many of the same areas of brain as are involved with physical sight. Imagery that originates from the senses and internally generated imagery may have a shared ontology at higher levels of cortical processing. Sound is analyzed in term of pressure waves sensed by the cochlea in the ear.

Cody and Johnstone (1982) and Rajan and Johnstone (1988a; 1988b) showed that constant acoustic stimulation that in (which evokes a strong MOCS response (Brown et al., 1998)) reduced the severity of acoustic trauma. This protection was negated in the presence of a chemical known to suppress the action of the olivocochlear bundle (OCB) (strychnine), implicating the action of the MOCS in protection of the cochlea from loud sounds. Further evidence for the auditory efferents having a protective role was provided by Rajan (1995a) and Kujawa and Liberman (1997).

400x400px Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes. Through mechanotransduction, hair cells detect movement in their environment. In mammals, the auditory hair cells are located within the spiral organ of Corti on the thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia called hair bundles that protrude from the apical surface of the cell into the fluid-filled cochlear duct.

When the stapes presses on the oval window, it causes the perilymph, the liquid of the inner ear to move. The middle ear thus serves to convert the energy from sound pressure waves to a force upon the perilymph of the inner ear. The oval window has only approximately 1/18 the area of the tympanic membrane and thus produces a higher pressure. The cochlea propagates these mechanical signals as waves in the fluid and membranes and then converts them to nerve impulses which are transmitted to the brain.

The utricular division of the auditory vesicle also responds to angular acceleration, as well as the endolymphatic sac and duct that connect the saccule and utricle. Beginning in the fifth week of development, the auditory vesicle also gives rise to the cochlear duct, which contains the spiral organ of Corti and the endolymph that accumulates in the membranous labyrinth. The vestibular wall will separate the cochlear duct from the perilymphatic scala vestibuli, a cavity inside the cochlea. The basilar membrane separates the cochlear duct from the scala tympani, a cavity within the cochlear labyrinth.

The actin filaments anchor to the terminal web and the top of the cell membrane and are arranged in grade of height. As sound waves propagate in the cochlea, the movement of endolymph fluid bends the stereocilia. If the direction of movement is towards the taller stereocilia, tension develops in the tip links, mechanically opening transduction channels near the tips. Cations from the endolymph flow into the cell, depolarizing the hair cell and triggering the release of neurotransmitters to nearby nerves, which send an electrical signal to the central nervous system.

In the cochlea, a shearing movement between the tectorial membrane and the basilar membrane deflects the stereocilia, affecting the tension on the tip-link filaments, which then open and close the non-specific ion channels. When tension increases, the flow of ions across the membrane into the hair cell rises as well. Such influx of ions causes a depolarization of the cell, resulting in an electrical potential that ultimately leads to a signal for the auditory nerve and the brain. The identity of the mechanosensitive channels in the stereocilia is still unknown.

An illustration of a cochlear implant In cases when a person is profoundly deaf or severely hard of hearing in both ears, a cochlear implant may be surgically implanted. Cochlear implants bypass most of the peripheral auditory system to provide a sense of sound via a microphone and some electronics that reside outside the skin, generally behind the ear. The external components transmit a signal to an array of electrodes placed in the cochlea, which in turn stimulates the cochlear nerve. In the case of an outer ear trauma, a craniofacial prosthesis may be necessary.

The pathway of recall associated with the retrieval of sound memories is the auditory system. Within the auditory system is the auditory cortex, which can be broken down into the primary auditory cortex and the belt areas. The primary auditory cortex is the main region of the brain that processes sound and is located on the superior temporal gyrus in the temporal lobe where it receives point-to-point input from the medial geniculate nucleus. From this, the primary auditory complex had a topographic map of the cochlea.

Gabriel Falloppius explaining one of his discoveries to the Cardinal Duke of Ferrara Falloppio's own work dealt mainly with the anatomy of the head. He added much to what was known before about the internal ear and described in detail the tympanum and its relations to the osseous ring in which it is situated. He also described minutely the circular and oval windows (fenestræ) and their communication with the vestibule and cochlea. He was the first to point out the connection between the mastoid cells and the middle ear.

The frequency range and sensitivity of the ear is dependent on the shape and arrangement of the middle-ear bones. In the reptilian lineage, hearing depends on the conduction of low-frequency vibrations through the ground or bony structures (such as the columella). By modifying the articular bone, quadrate bone, and columella into small ossicles, mammals were able to hear a wider range of high-frequency airborne vibrations. Hearing within mammals is further aided by a tympanum in the outer ear and newly evolved cochlea in the inner ear.

This area is called the helicotrema. This continuation at the helicotrema allows fluid being pushed into the vestibular duct by the oval window to move back out via movement in the tympanic duct and deflection of the round window; since the fluid is nearly incompressible and the bony walls are rigid, it is essential for the conserved fluid volume to exit somewhere. The lengthwise partition that divides most of the cochlea is itself a fluid-filled tube, the third duct. This central column is called the cochlear duct.

The temporal theory of hearing states that human perception of sound depends on temporal patterns with which neurons respond to sound in the cochlea. Therefore, in this theory, the pitch of a pure tone is determined by the period of neuron firing patterns—either of single neurons, or groups as described by the volley theory. Temporal or timing theory competes with the place theory of hearing, which instead states that pitch is signaled according to the locations of vibrations along the basilar membrane. Temporal theory was first suggested by August Seebeck.

The end result is that solutes from the blood, particularly chloride, are secreted into the lumen of these exocrine glands, increasing the luminal concentration of solutes and causing water to be secreted by osmosis. In addition to exocrine glands, NKCC1 is necessary for establishing the potassium-rich endolymph that bathes part of the cochlea, an organ necessary for hearing. Inhibition of NKCC1, as with furosemide or other loop diuretics, can result in deafness. NKCC1 is also expressed in many regions of the brain during early development, but not in adulthood.

By changing transmitter parameters, Frey was able to induce the "perception of severe buffeting of the head, without such apparent vestibular symptoms as dizziness or nausea". Other transmitter parameters induced a pins and needles sensation. Frey experimented with nerve-deaf subjects, and speculated that the human detecting mechanism was in the cochlea, but at the time of the experiment the results were inconclusive due to factors such as tinnitus. Auditory sensations of clicking or buzzing have been reported by some workers at modern day microwave transmitting sites that emit pulsed microwave radiation.

Waardenburg Syndrome Type 2D, a subtype of the Waardenburg syndrome, is a rare congenital disorder caused by a mutation in the SLUG (SNAI2) gene. It is characterized by the lack of pigmentation in the skin, hair, and eyes as well as the abnormalities in the outer wall of the cochlea. This subtype lacks the wide distance between the eyes, known as dystopia canthorum, that is observed in most patients with Waardenburg Syndrome. Those affected, exhibit varying degrees of deafness or complete hearing loss along with heterochromia and reports of early graying.

As one important mechanism, adaptation processes in the auditory brain that influence the dynamic range of neural responses are assumed to be distorted by irregular input from the inner ear. This is mainly caused by hearing loss related damage in the inner ear. The mechanism behind hyperacusis is not currently known, but it is suspected to be caused by damage to the inner ear and cochlea. It is theorized that type II afferent fibers become excited after damage to hair cells and synapses, triggering a release of ATP in response.

In the cochlea, the vibrations are transduced into electrical information through the firing of hair cells in the organ of Corti. The organ of Corti projects in an orderly fashion to structures in the brainstem (namely, the cochlear nuclei and the inferior colliculus), and from there to the medial geniculate nucleus of the thalamus and the primary auditory cortex. Adjacent sites on the organ of Corti, which are themselves selective for the sound frequency, are represented by adjacent neurons in the aforementioned CNS structures. This projection pattern has been termed tonotopy.

The primary form of hearing loss in otosclerosis is conductive hearing loss (CHL) whereby sounds reach the ear drum but are incompletely transferred via the ossicular chain in the middle ear, and thus partly fail to reach the inner ear (cochlea). This can affect one ear or both ears. On audiometry, the hearing loss is characteristically low-frequency, with higher frequencies being affected later. Sensorineural hearing loss (SNHL) has also been noted in patients with otosclerosis; this is usually a high-frequency loss, and usually manifests late in the disease.

Similarities between sensory processes of the skin and the auditory system suggest lateral inhibition could play a role in auditory processing. The basilar membrane in the cochlea has receptive fields similar to the receptive fields of the skin and eyes. Also, neighboring cells in the auditory cortex have similar specific frequencies that cause them to fire, creating a map of sound frequencies similar to that of the somatosensory cortex. Lateral inhibition in tonotopic channels can be found in the inferior colliculus and at higher levels of auditory processing in the brain.

From the anterior portion of the medulla oblongata, the glossopharyngeal nerve passes laterally across or below the flocculus, and leaves the skull through the central part of the jugular foramen. From the superior and inferior ganglia in jugular foramen, it has its own sheath of dura mater. The inferior ganglion on the inferior surface of petrous part of temporal is related with a triangular depression into which the aqueduct of cochlea opens. On the inferior side, the glossopharyngeal nerve is lateral and anterior to the vagus nerve and accessory nerve.

Sound waves enter the outer ear and travel through the external auditory canal until they reach the tympanic membrane, causing the membrane and the attached chain of auditory ossicles to vibrate. The motion of the stapes against the oval window sets up waves in the fluids of the cochlea, causing the basilar membrane to vibrate. This stimulates the sensory cells of the organ of Corti, atop the basilar membrane, to send nerve impulses to the central auditory processing areas of the brain, the auditory cortex, where sound is perceived and interpreted.

Sensory maps are areas of the brain which respond to sensory stimulation, and are spatially organized according to some feature of the sensory stimulation. In some cases the sensory map is simply a topographic representation of a sensory surface such as the skin, cochlea, or retina. In other cases it represents other stimulus properties resulting from neuronal computation and is generally ordered in a manner that reflects the periphery. An example is the somatosensory map which is a projection of the skin's surface in the brain that arranges the processing of tactile sensation.

Studies with different lengths of electrodes have shown that an insertion depth of 10 mm has a good chance of preserving residual hearing but on the other hand yields little benefit in speech understanding in comparison to the hearing aid only condition. Electrodes that can be inserted to a depth of 18–22 mm are a good compromise. The insertion depth also depends on the size of the cochlea of the patient, though a range of 18–22 mm can be used as a general rule of thumb for insertion in most cochleas.

The vestibulocochlear nerve (VIII) supplies information relating to balance and hearing via its two branches, the vestibular and cochlear nerves. The vestibular part is responsible for supplying sensation from the vestibules and semicircular canal of the inner ear, including information about balance, and is an important component of the vestibuloocular reflex, which keeps the head stable and allows the eyes to track moving objects. The cochlear nerve transmits information from the cochlea, allowing sound to be heard. When damaged, the vestibular nerve may give rise to the sensation of spinning and dizziness (vertigo).

In some species such as the bullfrog, the size of the tympanum indicates the sex of the frog; males have tympani that are larger than their eyes while in females, the eyes and tympani are much the same size. A noise causes the tympanum to vibrate and the sound is transmitted to the middle and inner ear. The middle ear contains semicircular canals which help control balance and orientation. In the inner ear, the auditory hair cells are arranged in two areas of the cochlea, the basilar papilla and the amphibian papilla.

A third, evolutionarily younger, function of the basilar membrane is strongly developed in the cochlea of most mammalian species and weakly developed in some bird species: Fritzsch B: The water-to-land transition: Evolution of the tetrapod basilar papilla; middle ear, and auditory nuclei. In: the dispersion of incoming sound waves to separate frequencies spatially. In brief, the membrane is tapered and it is stiffer at one end than at the other. Furthermore, sound waves travelling to the "floppier" end of the basilar membrane have to travel through a longer fluid column than sound waves travelling to the nearer, stiffer end.

When sensorineural hearing loss (damage to the cochlea or in the brain) is present, the perception of loudness is altered. Sounds at low levels (often perceived by those without hearing loss as relatively quiet) are no longer audible to the hearing impaired, but sounds at high levels often are perceived as having the same loudness as they would for an unimpaired listener. This phenomenon can be explained by two theories, called "loudness recruitment and softness imperception" Loudness recruitment posits that loudness grows more rapidly for certain listeners than normal listeners with changes in level. This theory has been accepted as the classical explanation.

The basilar membrane within the cochlea contains the first of these specializations for echo information processing. In bats that use CF signals, the section of the membrane that responds to the frequency of returning echoes is much larger than the region of response for any other frequency. For example, in the greater horseshoe bat, Rhinolophus ferrumequinum, there is a disproportionately lengthened and thickened section of the membrane that responds to sounds around 83 kHz, the constant frequency of the echo produced by the bat's call. This area of high sensitivity to a specific, narrow range of frequency is known as an "acoustic fovea".

Two proteins have been found to play a major role in toothed whale echolocation. Prestin, a motor protein of the outer hair cells of the inner ear of the mammalian cochlea, has an association between the number of nonsynonymous substitutions and hearing sensitivity. It has undergone two clear episodes of accelerated protein evolution in cetaceans: on the ancestral branch of odontocetes and on the branch leading to delphinioidae. The first episode of acceleration is connected to odontocete divergence, when echolocation first developed, and the second occurs with the increase in echolocation frequency seen in the family Delphinioidae.

The presence of dehiscence can be detected by a high definition (0.6 mm or less) coronal CT scan of the temporal bone, currently the most reliable way to distinguish between superior canal dehiscence syndrome (SCDS) and other conditions of the inner ear involving similar symptoms such as Ménière's disease, perilymphatic fistula and cochlea-facial nerve dehiscence. Other diagnostic tools include the vestibular evoked myogenic potential or VEMP test, videonystagmography (VNG), electrocochleography (ECOG) and the rotational chair test. An accurate diagnosis is of great significance as unnecessary exploratory middle ear surgery may thus be avoided. Several of the symptoms typical to SCDS (e.g.

Echolocating animals can jam themselves in a number of ways. Bats, for example, produce some of the loudest sounds in nature, and then they immediately listen for echoes that are hundreds of times fainter than the sounds they emit. To avoid deafening themselves, whenever a bat makes an echolocation emission, a small muscle in the bat's middle ear (the stapedius muscle) clamps down on small bones called ossicles, which normally amplify sounds between the ear drum and the cochlea. This dampens the intensity of the sounds that the bat hears during this time, preserving hearing sensitivity to target echoes.

A hearing screening is considered valid, according to McPherson and Olusanya (2008), "if it detects the majority of subjects with the target disorder (high sensitivity) and excludes most subjects without the disorder (high specificity) and if a positive test indicates the presence of the disorder (high positive predictive value)." Two objective screening tests available for use in infants are otoacoustic emissions (OAEs) and auditory brainstem response (ABR). An OAE is an electrophysiologic measure of the integrity of the outer hair cells in the cochlea. Two types of OAEs are transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs).

The second mechanism is a non-linear active mechanism, which is primarily dependent on the functioning of the OHCs, and also the general physiological condition of the cochlea itself. The base and apex of the basilar membrane differ in stiffness and width, which cause the basilar membrane to respond to varying frequencies differently along its length. The base of the basilar membrane is narrow and stiff, resulting in it responding best to high frequency sounds. The apex of the basilar membrane is wider and much less stiff in comparison to the base, causing it to respond best to low frequencies.

The earliest evidence available for primates depicts a short cochlea with prominent laminae, suggesting that they had good high-frequency sensitivity as opposed to low- frequency sensitivity. After this, over a period of around 60 million years, evidence suggests that primates developed longer cochleae and less prominent laminae, which means that they had an improvement in low-frequency sensitivity and a decrease in high-frequency sensitivity. By the early Miocene period, the cycle of the elongation of the cochleae and the deterioration of the laminae was completed. Evidence shows that primates have had an increasing cochlear volume to body mass ratio over time.

Jonas Frisén and his colleagues at the Karolinska Institute in Stockholm provided evidence that ependymal cells act as reservoir cells in the forebrain, which can be activated after stroke and as in vivo and in vitro stem cells in the spinal cord. However, these cells did not self- renew and were subsequently depleted as they generated new neurons, thus failing to satisfy the requirement for stem cells. One study observed that ependymal cells from the lining of the lateral ventricle might be a source for cells which can be transplanted into the cochlea to reverse hearing loss.

When exposed to noise, the human ear's sensitivity to sound is decreased, corresponding to an increase in the threshold of hearing. This shift is usually temporary but may become permanent. A natural physiological reaction to these threshold shifts is vasoconstriction, which will reduce the amount of blood reaching the hair cells of the organ of Corti in the cochlea. With the resultant oxygen tension and diminished blood supply reaching the outer hair cells, their response to sound levels is lessened when exposed to loud sounds, rendering them less effective and putting more stress on the inner hair cells.

Presbycusis (also spelled presbyacusis, from Greek presbys "old" + akousis "hearing"Online Etymology Dictionary, Presbycousis), or age-related hearing loss, is the cumulative effect of aging on hearing. It is a progressive and irreversible bilateral symmetrical age-related sensorineural hearing loss resulting from degeneration of the cochlea or associated structures of the inner ear or auditory nerves. The hearing loss is most marked at higher frequencies. Hearing loss that accumulates with age but is caused by factors other than normal aging (nosocusis and sociocusis) is not presbycusis, although differentiating the individual effects of distinct causes of hearing loss can be difficult.

The quadrate is vertically oriented. The coronoid process of the lower jaw is strongly protruding. The side of the braincase largely consists of cartilage instead of bone, so that many brain nerves must have had their exits in a single large opening, rather than separate small ones. The inner ear is very large compared with the skull as a whole and differs from that of all other known Dinosauria in the ear vestibule not being separated from the brain cavity, the floor for the cochlea not being made of bone and the vestibule being so large that the semicircular canals are shortened.

As the first stage of CASA processing, the cochleagram creates a time-frequency representation of the input signal. By mimicking the components of the outer and middle ear, the signal is broken up into different frequencies that are naturally selected by the cochlea and hair cells. Because of the frequency selectivity of the basilar membrane, a filter bank is used to model the membrane, with each filter associated with a specific point on the basilar membrane. Since the hair cells produce spike patterns, each filter of the model should also produce a similar spike in the impulse response.

The ossicles are classically supposed to mechanically convert the vibrations of the eardrum into amplified pressure waves in the fluid of the cochlea (or inner ear), with a lever arm factor of 1.3. Since the effective vibratory area of the eardrum is about 14 fold larger than that of the oval window, the sound pressure is concentrated, leading to a pressure gain of at least 18.1. The eardrum is merged to the malleus, which connects to the incus, which in turn connects to the stapes. Vibrations of the stapes footplate introduce pressure waves in the inner ear.

The saccule is the smaller sized vestibular sac (the utricle being the other larger size vestibular sac); it is globular in form, and lies in the recessus sphæricus near the opening of the scala vestibuli of the cochlea. Its anterior part exhibits an oval thickening, the macula of saccule (or saccular macula), to which are distributed the saccular filaments of the acoustic nerve. The vestibule is a region of the inner ear which contains the saccule and the utricle, each of which contain a macula to detect linear acceleration.Its function is to detect vertical linear acceleration.

The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation. The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.

The human ear consists of three parts—the outer ear, middle ear and inner ear. The ear canal of the outer ear is separated from the air-filled tympanic cavity of the middle ear by the eardrum. The middle ear contains the three small bones—the ossicles—involved in the transmission of sound, and is connected to the throat at the nasopharynx, via the pharyngeal opening of the Eustachian tube. The inner ear contains the otolith organs—the utricle and saccule—and the semicircular canals belonging to the vestibular system, as well as the cochlea of the auditory system.

These form bipolar neurons which supply sensation to parts of the inner ear (namely the sensory parts of the semicircular canals, macular of the utricle and saccule, and organ of Corti). The nerve begins to form around the 28th day. ;Molecular regulation Most of the genes responsible for the regulation of inner ear formation and its morphogenesis are members of the homeobox gene family such as Pax, Msx and Otx homeobox genes. The development of inner ear structures such as the cochlea is regulated by Dlx5/Dlx6, Otx1/Otx2 and Pax2, which in turn are controlled by the master gene Shh.

The mechanical role of the tectorial membrane in hearing is yet to be fully understood, and traditionally was neglected or downplayed in many models of the cochlea. However, recent genetic , mechanical and mathematical studies have highlighted the importance of the TM for healthy auditory function in mammals. Mice that lack expression of individual glycoproteins exhibit hearing abnormalities, including, most notably, enhanced frequency selectivity in Tecb−/− mice, which lack expression of β-tectorin. In vitro investigations of the mechanical properties of the TM have demonstrated the ability of isolated sections of TM to support travelling waves at acoustically relevant frequencies.

There, he led the speech recognition project. In 1988, Lyon moved to the Apple Advanced Technology Group and led the Perception Systems group, where he worked mainly on auditory and sound processing. During this period he published a paper with Carver Mead describing an analog cochlea which modeled the propagation of sound in the inner ear and the conversion of acoustic energy into neural representations. The paper received the Best Paper Award from the IEEE Signal Processing Society in 1990 and formed a foundation for later work applying such models to hearing aids, cochlear implants, and other speech recognition hardware devices.

The outer ear funnels sound vibrations to the eardrum, increasing the sound pressure in the middle frequency range. The middle-ear ossicles further amplify the vibration pressure roughly 20 times. The base of the stapes couples vibrations into the cochlea via the oval window, which vibrates the perilymph liquid (present throughout the inner ear) and causes the round window to bulb out as the oval window bulges in. Vestibular and tympanic ducts are filled with perilymph, and the smaller cochlear duct between them is filled with endolymph, a fluid with a very different ion concentration and voltage.

400x400px The cochlea is filled with a watery liquid, the endolymph, which moves in response to the vibrations coming from the middle ear via the oval window. As the fluid moves, the cochlear partition (basilar membrane and organ of Corti) moves; thousands of hair cells sense the motion via their stereocilia, and convert that motion to electrical signals that are communicated via neurotransmitters to many thousands of nerve cells. These primary auditory neurons transform the signals into electrochemical impulses known as action potentials, which travel along the auditory nerve to structures in the brainstem for further processing.

As the study of the cochlea should fundamentally be focused at the level of hair cells, it is important to note the anatomical and physiological differences between the hair cells of various species. In birds, for instance, instead of outer and inner hair cells, there are tall and short hair cells. There are several similarities of note in regard to this comparative data. For one, the tall hair cell is very similar in function to that of the inner hair cell, and the short hair cell, lacking afferent auditory-nerve fiber innervation, resembles the outer hair cell.

The major input to the cochlear nucleus is from the auditory nerve, a part of cranial nerve VIII (the vestibulocochlear nerve). The auditory nerve fibers form a highly organized system of connections according to their peripheral innervation of the cochlea. Axons from the spiral ganglion cells of the lower frequencies innervate the ventrolateral portions of the ventral cochlear nucleus and lateral-ventral portions of the dorsal cochlear nucleus. The axons from the higher frequency organ of corti hair cells project to the dorsal portion of the ventral cochlear nucleus and the dorsal-medial portions of the dorsal cochlear nucleus.

Water has different acoustic properties to air. Sound from an underwater source can propagate relatively freely through body tissues where there is contact with the water as the acoustic properties are similar. When the head is exposed to the water, a significant part of sound reaches the cochlea independently of the middle ear and eardrum, but some is transmitted by the middle ear. Bone conduction plays a major role in underwater hearing when the head is in contact with the water (not inside a helmet), but human hearing underwater, in cases where the diver’s ear is wet, is less sensitive than in air.

Onychonycteris finneyi was the strongest evidence so far in the debate on whether bats developed echolocation before or after they evolved the ability to fly. O. finneyi had well-developed wings, and could clearly fly, but lacked the enlarged cochlea of all extant echolocating bats, closely resembling the old world fruit bats which do not echolocate. This indicates that early bats could fly before they could echolocate. However, an independent evaluation of the Onychonycteris reference fossil in 2010 provided some evidence for other bone structures indicative of laryngeal echolocation, raising the possibility that Onychonycteris finneyi possessed the ability to echolocate after all.

Diagram of signal processing in the auditory system. The human brain is provided with information about light, sound, the chemical composition of the atmosphere, temperature, the position of the body in space (proprioception), the chemical composition of the bloodstream, and more. In other animals additional senses are present, such as the infrared heat-sense of snakes, the magnetic field sense of some birds, or the electric field sense mainly seen in aquatic animals. Each sensory system begins with specialized receptor cells, such as photoreceptor cells in the retina of the eye, or vibration-sensitive hair cells in the cochlea of the ear.

The inner ear has wide semicircular canals like non-human apes, as well as loose turns at the terminal end of the cochlea like humans. Such a mix may reflect habitual locomotion both in the trees and walking while upright because inner ear anatomy affects the vestibular system (sense of balance). A. africanus had a prognathic jaw (it jutted out), a somewhat dished face (the cheek were inflated, causing the nose to be at the bottom of a dip), and a defined brow ridge. The temporal lines running across either side of the braincase are raised as small crests.

The sheath was developed from a connective tissue graft from the person's own body that was placed around the electrode bundle where it entered the cochlea. The first cochlear implant was invented and developed by Dr. William F. House. House's device was a single electrode configuration, compared to the multiple electrode device developed by Clark. Clark's first multi-channel cochlear implant operation was done at the Royal Victorian Eye and Ear Hospital in 1978 by Clark and Dr Brian Pyman.G.M. Clark, B.C. Pyman, Q.R. Bailey, The surgery for multiple-electrode cochlear implantations, The Journal of Laryngology and Otology, Volume 93, Issue 03, pp.

This discovery established that the timing of electrical stimuli was important for low pitch when this had been difficult to determine with sound. But discrimination of pitch up to 4000 Hz is required for speech understanding, so Clark emphasised early in the development of his cochlear implant that "place coding through multi-channel stimulation" would have to be used for the important mid-to-high speech frequencies. Clark and Tong next discovered that place of stimulation was experienced as timbre, but without a strong pitch sensation. The patient could identify separate sensations according to the site of stimulation in the cochlea.

Conventional hearing aids which amplify sound can cause distortion for these patients. Therefore, the traditional treatment approach has been a prosthetic device called Baha, which replaces the function of the impaired ear by using a well-established principle called bone conduction to re-route sound through the skull bones to the functional cochlea. The Baha bone conduction prosthetic devices are used rather than hearing aids because conventional hearing aids are clinically inappropriate for these patients. The Baha surgery can cause complications that range from skin reaction to infection, to abscess, to complete re-implantation or revision of the Baha post.

Neurons at one end of the auditory cortex respond best to low frequencies; neurons at the other respond best to high frequencies. There are multiple auditory areas (much like the multiple areas in the visual cortex), which can be distinguished anatomically and on the basis that they contain a complete "frequency map." The purpose of this frequency map (known as a tonotopic map) likely reflects the fact that the cochlea is arranged according to sound frequency. The auditory cortex is involved in tasks such as identifying and segregating "auditory objects" and identifying the location of a sound in space.

Each part of the basilar membrane, together with the surrounding fluid, can therefore be thought of as a "mass-spring" system with different resonant properties: high stiffness and low mass, hence high resonant frequencies at the near (base) end, and low stiffness and high mass, hence low resonant frequencies, at the far (apex) end. This causes sound input of a certain frequency to vibrate some locations of the membrane more than other locations. The distribution of frequencies to places is called the tonotopic organization of cochlea. Sound- driven vibrations travel as waves along this membrane, along which, in humans, lie about 3,500 inner hair cells spaced in a single row.

The channel signals are then subjected to instantaneous compression to map them into the limited dynamic range for each channel. Cochlear implants differ than hearing aids in that the entire acoustic hearing is replaced with direct electric stimulation of the auditory nerve, achieved via an electrode array placed inside the cochlea. Hence, here, other factors than device signal processing also strongly contribute to overall hearing, such as etiology, nerve health, electrode configuration and proximity to the nerve, and overall adaptation process to an entirely new mode of hearing. Almost all information in cochlear implants is conveyed by the envelope fluctuations in the different channels.

Other options besides sign language for kids with prelingual deafness include the use hearing aids to strengthen remaining sensory cells or cochlear implants to stimulate the hearing nerve directly. Cochlear Implants are hearing devices that are placed behind the ear and contain a receiver and electrodes which are placed under the skin and inside the cochlea. Despite these developments, there is still a risk that prelingually deaf children are may not develop good speech and speech reception skills. Although cochlear implants produce sounds, they are unlike typical hearing and deaf and hard of hearing people must undergo intensive therapy in order to learn how to interpret these sounds.

His group holds several first and best world records in the fields of medical devices, medical electronics, ultra low power, analog, and bio-inspired design . He has authored more than 139 technical publications and is an inventor on more than forty two awarded patents. He is the inventor of the RF Cochlea, a rapid radio-frequency spectrum analyzer inspired by the human ear . His book Ultra Low Power Bioelectronics: Fundamentals, Biomedical Applications, and Bio- inspired Systems is published by Cambridge University Press and provides a broad and deep treatment of the fields of analog, ultra low power, biomedical, biological, energy-harvesting and bio-inspired design.

Sounds are transmitted via a receiver attached from the arm of the spectacles which are fitted firmly behind the boney portion of the skull at the back of the ear, (mastoid process) by means of pressure, applied on the arm of the spectacles. The sound is passed from the receiver on the arm of the spectacles to the inner ear (cochlea), via the bony portion. The process of transmitting the sound through the bone requires a great amount of power. Bone conduction aids generally have a poorer high pitch response and are therefore best used for conductive hearing losses or where it is impractical to fit standard hearing aids.

The common English phrase "it warms the cockles of my heart", is used to mean that a feeling of deep-seated contentment has been generated. Differing derivations of this phrase have been proposed, either directly from the perceived heart- shape of a cockleshell, or indirectly (the scientific name for the type genus of the family is Cardium, from the Latin for heart), or from the Latin diminutive of the word heart, corculum. Another proposed derivation is from the Latin for the ventricles of the heart, cochleae cordis, where the second word is an inflected form of cor, heart, while cochlea is the Latin for snail.

The binaural auditory system is highly dynamic and capable of rapidly adjusting tuning properties depending on the context in which sounds are heard. Each eardrum moves one-dimensionally; the auditory brain analyzes and compares movements of both eardrums to extract physical cues and synthesize auditory objects. When stimulation from a sound reaches the ear, the eardrum deflects in a mechanical fashion, and the three middle ear bones (ossicles) transmit the mechanical signal to the cochlea, where hair cells transform the mechanical signal into an electrical signal. The auditory nerve, also called the cochlear nerve, then transmits action potentials to the central auditory nervous system.

Action potentials originate in the hair cells of the cochlea and propagate to the brainstem; both the timing of these action potentials and the signal they transmit provide information to the SOC about the orientation of sound in space. The processing and propagation of action potentials is rapid, and therefore, information about the timing of the sounds that were heard, which is crucial to binaural processing, is conserved. Each eardrum moves in one dimension, and the auditory brain analyzes and compares the movements of both eardrums in order to synthesize auditory objects. This integration of information from both ears is the essence of binaural fusion.

Auditory evoked potentials (AEP) can be used to trace the signal generated by a sound through the ascending auditory pathway. The evoked potential is generated in the cochlea, goes through the cochlear nerve, through the cochlear nucleus, superior olivary complex, lateral lemniscus, to the inferior colliculus in the midbrain, on to the medial geniculate body, and finally to the cortex. Auditory evoked potentials (AEPs) are a subclass of event-related potentials (ERPs). ERPs are brain responses that are time-locked to some "event", such as a sensory stimulus, a mental event (such as recognition of a target stimulus), or the omission of a stimulus.

Cranial endocast of N. mckinleyi In 2018, the holotype braincase of Nothronychus mckinleyi was re-examined by Smith and colleagues updating numerous basicranial and soft-tissues aspects. They noted that the braincase has particularly large pneumatic chambers on the sensorial areas, suggesting that the increased tympanic systems would result in optimal low frequency sound reception, possibly infrasound, and in complex social behavior. The enlarged cochlea and presence of enlarged pneumatic chambers near the middle ear also supports this insight. Smith and colleagues established an average hearing frequency of 1100 to 1450 Hz and upper limits of 3000 to 3700 Hz. They stated however, that these estimates could be slightly exaggerated.

Similarly to vision loss, hearing loss can vary from full or partial inability to detect some or all frequencies of sound which can typically be heard by members of their species. For humans, this range is approximately 20 Hz to 20 kHz at ~6.5 dB, although a 10 dB correction is often allowed for the elderly. Primary causes of hearing loss due to an impaired sensory system include long-term exposure to environmental noise, which can damage the mechanoreceptors responsible for receiving sound vibrations, as well as multiple diseases, such as CMV or meningitis, which damage the cochlea and auditory nerve, respectively. Hearing loss may be gradual or sudden.

Conductive hearing ability is mediated by the middle ear composed of the ossicles: the malleus, the incus, and the stapes. Sensorineural hearing ability is mediated by the inner ear composed of the cochlea with its internal basilar membrane and attached cochlear nerve (cranial nerve VIII). The outer ear consisting of the pinna, ear canal, and ear drum or tympanic membrane transmits sounds to the middle ear but does not contribute to the conduction or sensorineural hearing ability save for hearing transmissions limited by cerumen impaction (wax collection in the ear canal). The Weber test has had its value as a screening test questioned in the literature.

Cross-section through the spiral organ of Corti at greater magnification, showing position of the hair cells on the basement membrane. The organ of Corti is located in the scala media of the cochlea of the inner ear between the vestibular duct and the tympanic duct and is composed of mechanosensory cells, known as hair cells. Strategically positioned on the basilar membrane of the organ of Corti are three rows of outer hair cells (OHCs) and one row of inner hair cells (IHCs). Separating these hair cells are supporting cells: Deiters cells, also called phalangeal cells, which separate and support both the OHCs and the IHCs.

They also differentiate into the stria vascularis of the cochlea, the nerves and glia of the intestines (myenteric plexus), Schwann cells, which myelinate the peripheral nervous system to allow sufficient conductivity, odontoblasts, which produce dentin deep in the teeth, some neuroendocrine cells, connective tissue around the salivary, lacrimal, pituitary, thymus and thyroid glands, connective tissue of the eye, such as the stroma of the iris and cornea and the trabecular meshwork, and melanocytes, including those in the stroma of the iris that give rise to brown eye colour through melanin. Neural crest cells also have a role in muscle formation, including the wall muscle of certain cardiac arteries.

In the termite Zootermopsis angusticollis and the cockroach Periplaneta americana, the vibration is perceived after about 10-20 milliseconds and stops being perceived after one or two seconds. There are two types of cells with different spatial orientation in the organ; possibly, oscillation causes the cells to shift with respect to each other and generate a signal. Some early research claimed that the sensitivity of the Periplaneta subgenual organ might be far higher than the threshold of about one atom diameter determined for cochlear cells; newer investigation indicated that such a sensitivity may have been the result of artifacts, with the actual sensitivity being comparable to the cochlea.

Later he was on the faculty of Washington University in St. Louis. Charlie Molnar was also well known as a pioneer in the modeling of the auditory system, especially numerical models of the function of the cochlea (the inner ear). When he died in 1996, he was working at Sun Microsystems on asynchronous circuits with Ivan Sutherland. Molnar received a bachelor's degree (1956) and a master's degree (1957) in electrical engineering from Rutgers University, where he was a member of the Cap and Skull Society,Cap and Skull Honor Society of Rutgers College and received a doctoral degree (1966) from MIT in electrical engineering.

In the auditory system of bats, like in auditory systems of other vertebrates, primary sensory afferent neurons, which receive inputs from hair cells from a restricted region of the organ of Corti in the cochlea, are the simple feature detectors. These structures are sensitive to a restricted range of frequencies and therefore function as tuned filters. Experimentally, Nobuo Suga and his colleagues (1990) noted that various constant frequency (CF) and frequency modulated (FM) harmonics excited different parts of the basilar membrane because of the frequency difference in the call. Auditory nerve fibers take this slightly-processed sensory information to the cochlear nucleus where information either converges or diverges into parallel pathways.

Hearing Research, 17(3), 237–247. doi: 10.1016/0378-5955(85)90068-1 The temporal lobes of the owls were then removed from the skulls, post-fixed in 1% osmium tetroxide, dehydrated, then embedded in Araldite to study the anatomy of the inner ear. This study revealed that the basilar papilla of barn owls has two very unique features being a proliferation of lenticular cells and a thickening of the basilar membrane. The cochlear duct of the owl contains the basilar papilla, the tectorial membrane, the tegmentum vasculum, and the macula of the lagena. The basilar papilla of the cochlea was measured to be 9.5-11.5 mm long.

The vestibulocochlear nerve has two components, the auditory and vestibular portions. Most schwannomas start out as intracanalicular, and growth compresses the nerve against the bony canal, so the first symptoms of the tumor are unilateral sensorineural hearing loss or disturbances in balance. It may also compress the labyrinthine artery (main artery supplying the vestibular apparatus and cochlea of the inner ear) which passes through the auditory canal, resulting in ischemia or infarction ('heart attack' of the ear, resulting in death of the supplied tissue). As intracanalicular tumors grow, they tend to expand into the cerebellopontine angle (CPA), leading to their characteristic "ice-cream-cone like" appearance on a radiograph.

The hearing loss associated with congenital aural atresia is a conductive hearing loss—hearing loss caused by inefficient conduction of sound to the inner ear. Essentially, children with aural atresia have hearing loss because the sound cannot travel into the (usually) healthy inner ear—there is no ear canal, no eardrum, and the small ear bones (malleus/hammer, incus/anvil, and stapes/stirrup) are underdeveloped. "Usually" is in parentheses because rarely, a child with atresia also has a malformation of the inner ear leading to a sensorineural hearing loss (as many as 19% in one study). Sensorineural hearing loss is caused by a problem in the inner ear, the cochlea.

In 1961, he was awarded the Nobel Prize in Physiology or Medicine for his research on the function of the cochlea in the mammalian hearing organ. The Vacanti mouse was a laboratory mouse that had what looked like a human ear grown on its back. The "ear" was actually an ear-shaped cartilage structure grown by seeding cow cartilage cells into a biodegradable ear-shaped mold and then implanted under the skin of the mouse; then the cartilage naturally grew by itself. It was developed as an alternative to ear repair or grafting procedures and the results met with much publicity and controversy in 1997.

At postnatal day two (P2), the immature calyx of Held is formed, easily distinguished by its characteristic sealed-spoon morphology. The primary synaptic contacts that form the calyx are assembled between neurons of the MNTB (medial nucleus of the trapezoid body) and VCN (ventral cochlear nerve), eventually connecting with one another by projecting across the midline of the two areas. These associations begin to appear immediately after VCN neurons have been generated; one can observe the earliest formation of these contacts around embryonic day 17 (E17). These neuronal connections, which make up an important area of the cochlea, form branches with one another that terminate in the calyx of Held.

The cochlear nuclear (CN) complex comprises two cranial nerve nuclei in the human brainstem, the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). The ventral cochlear nucleus is unlayered whereas the dorsal cochlear nucleus is layered. Auditory nerve fibers, fibers that travel through the auditory nerve (also known as the cochlear nerve or eighth cranial nerve) carry information from the inner ear, the cochlea, on the same side of the head, to the nerve root in the ventral cochlear nucleus. At the nerve root the fibers branch to innervate the ventral cochlear nucleus and the deep layer of the dorsal cochlear nucleus.

In 1948, Gold hypothesized that the ear operates by "regeneration", in that electromechanical action occurs when electrical energy is used to counteract the effects of damping.. Although Gold won a prize fellowship from Trinity College for his thesis on the regeneration and obtained a junior lectureship at the Cavendish Laboratory, his theory was widely ignored by ear specialists and physiologists, such as future Nobel Prize winner Georg von Békésy, who did not believe the cochlea operated under a feedback system.. In the 1970s, researchers discovered that Gold's hypothesis had been correct – the ear contained microscopic hair cells that operated on a feedback mechanism to generate resonance.

Sound is the perceptual result of mechanical vibrations traveling through a medium such as air or water. Through the mechanisms of compression and rarefaction, sound waves travel through the air, bounce off the pinna and concha of the exterior ear, and enter the ear canal. The sound waves vibrate the tympanic membrane (ear drum), causing the three bones of the middle ear to vibrate, which then sends the energy through the oval window and into the cochlea where it is changed into a chemical signal by hair cells in the organ of Corti, which synapse onto spiral ganglion fibers that travel through the cochlear nerve into the brain.

The ear filters incoming sound into different frequencies: a given place in the cochlea, and a given auditory nerve fibre, respond only to a limited range of frequencies. Consequently, researchers have examined the cues that are generated by mixtures of speech and noise at the two ears within a narrow frequency band around the signal. When a signal and narrowband noise are added, a vector summation occurs in which the resultant amplitude and phase differ from those of the noise or signal alone. For a binaural unmasking stimulus, the differences between the interaural parameters of the signal and noise mean that there will be a different vector summation at each ear.

The auditory hair cells in the cochlea are at the core of the auditory system's special functionality (similar hair cells are located in the semicircular canals). Their primary function is mechanotransduction, or conversion between mechanical and neural signals. The relatively small number of the auditory hair cells is surprising when compared to other sensory cells such as the rods and cones of the visual system. Thus the loss of a lower number (in the order of thousands) of auditory hair cells can be devastating while the loss of a larger number of retinal cells (in the order to hundreds of thousands) will not be as bad from a sensory standpoint.

The vestibulocochlear nerve is accompanied by the labyrinthine artery, which usually branches off from the anterior inferior cerebellar artery (AICA) at the cerebellopontine angle, and then goes with the 7th nerve through the internal acoustic meatus to the internal ear. The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia. Processes from the organ of Corti conduct afferent transmission to the spiral ganglia. It is the inner hair cells of the organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound.

Tinnitus can also be categorised by the way it sounds in one's ear, pulsatile tinnitus which is caused by the vascular nature of Glomus tumours and non-pulsatile tinnitus which usually sounds like crickets, the sea and bees. Though the pathophysiology of tinnitus isn't known, noise exposure can be a contributing factor, therefore tinnitus can be associated with hearing loss, generated by the cochlea and central nervous system (CNS). High frequency hearing loss causes a high pitched tinnitus and low frequency hearing loss causes a roaring tinnitus. Noise- induced tinnitus can be temporary or permanent depending on the type and amount of noise a person was exposed to.

Cochlear implants also filter the input signal into frequency channels. Usually, the ENVp of the signal in each channel is transmitted to the implanted electrodes in the form an electrical pulses of fixed rate that are modulated in amplitude or duration. Information about TFSp is discarded. This is justified by the observation that people with cochlear implants have a very limited ability to process TFSp information, even if it is transmitted to the electrodes, perhaps because of a mismatch between the temporal information and the place in the cochlea to which it is delivered Reducing this mismatch may improve the ability to use TFSp information and hence lead to better pitch perception.

Transmembrane channel-like protein 1 is a protein that in humans is encoded by the TMC1 gene. TMC1 contains six transmembrane domains with both the C and N termini on the endoplasmic side of the membrane, as well as a large loop between domains 4 and 5. This topology is similar to that of transient receptor potential channels (TRPs), a family of proteins involved in the perception of senses such as temperature, taste, pressure, and vision. TMC1 has been located in the post-natal mouse cochlea, and knockouts for TMC1 and TMC2 result in both auditory and vestibular deficits (hearing loss and balance issues) indicating TMC1 is a molecular part of auditory transduction.

At all but low frequencies, the neural measure averages over multiple cycles to give the equivalent of rectification followed by averaging (low-pass filtering). Over the entire cochlea, response shows as a pattern that varies more slowly that the applied frequency but that does follow the envelope of the applied signal. Each group of cells can give rise to a semi-periodic wave that can be analyzed by neurons in the brain. The total pattern that arises from a sound can thus be thought of as a two- dimensional pattern in time with one axis being the distance along the basilar membrane and the other being distance along some sequence of neurons.

This high concentration is not found in inner hair cells, and is also lacking in all hair cell types of non-mammals. Prestin also has a role in motility, which evolved a greater importance in the motor function in land vertebrates, but this developed vastly differently in different lineages. In certain birds and mammals, prestin function as both transporters and motors, but the strongest evolution to robust motor dynamics only evolved in therian mammals. It is hypothesized that this motor system is significant to the therian cochlea at high frequencies because of the distinctive cellular and bony composition of the organ of Corti that allows prestin to intensify the movements of the whole structure.

The classic compositional parameters of tempo, meter, and rhythm are pushed into the background by this broadening of perspective through a psychological perception of time. After his work with structure and time Gunnar Geisse again delved into questions concerning the fundamental functions of harmony. Searching for answers within nature since 2003, he has occupied himself with the non-linear phenomena of combination-tones - these are tones that are formed in the cochlea of the inner ear as an extension of the original acoustic signal. The combination-tones are the missing building blocks which, when added to his use of partial-tone rows and partial-tone matrixes, complete Geisse's set of harmonic compositional tools.

This is because the cochlea in our inner ear analyzes sounds in terms of spectral content, each "hair-cell" responding to a narrow band of frequencies known as a critical band. The high-frequency bands are wider in absolute terms than the low- frequency bands, and therefore "collect" proportionately more power from a noise source. However, when more than one critical band is stimulated, the signals to the brain add the various bands to produce the impressions of loudness. For these reasons Equal-loudness curves derived using noise bands show an upwards tilt above 1 kHz and a downward tilt below 1 kHz when compared to the curves derived using pure tones.

A cochlear implant is placed surgically inside the cochlea, which is the part of the inner ear that converts sound to neural signals. There is much debate regarding the linguistic conditions under which deaf children acquire spoken language via cochlear implantation. A singular, yet to be replicated, study concluded that long-term use of sign language impedes the development of spoken language and reading ability in deaf and hard of hearing children, and that using sign language is not at all advantageous, and can be detrimental to language development. However, studies have found that sign language exposure actually facilitates the development of spoken language of deaf children of deaf parents who had exposure to sign language from birth.

There are two known patients identified with mutations in both copies of SNAI2 (classified as type 2D); these individuals presented with Waardenburg syndrome type 2 but did not have hair pigmentation deficiencies. When Waardenburg syndrome type 2 is caused by a mutation in SOX10 (classified as type 2E), it can on some occasions present with multiple neurological symptoms. These can include developmental delay, early childhood nystagmus, increased muscle tone, white matter anomalies or hypomyelination in the brain, autistic-like behaviour and the underdevelopment or complete absence of many inner-ear structures such as the vestibular system or cochlea. Lack of a sense of smell (anosmia) due to a missing olfactory bulb in the brain may also be present.

Semi circular ducts, which are connected directly to the cochlea, can interpret and convey to the brain information about equilibrium by a similar method as the one used for hearing. Hair cells in these parts of the ear protrude kinocilia and stereocilia into a gelatinous material that lines the ducts of this canal. In parts of these semi circular canals, specifically the maculae, calcium carbonate crystals known as statoconia rest on the surface of this gelatinous material. When tilting the head or when the body undergoes linear acceleration, these crystals move disturbing the cilia of the hair cells and, consequently, affecting the release of neurotransmitter to be taken up by surrounding sensory nerves.

Kujawa's research program aims to find out aging and noise exposure alter inner ear structures and functions, how genetic factors affect vulnerability to hearing loss, and how neural processes can be manipulated for purposes of treatment or prevention. Noise-induced and age-related hearing loss are the most common forms of hearing loss seen in adult patients and they often co-exist in the same patients. In collaboration with M. Charles Liberman and other researchers, Kujawa has examined the vulnerability of the synapses that connect hair cells in the cochlea to auditory nerve fibers. Their research has shown that cochlear synapses may be temporarily or permanently damaged from overexposure to intense sound.

A complex sound is split into different frequency components and these components cause a peak in the pattern of vibration at a specific place on the cilia inside the basilar membrane within the cochlea. These components are then coded independently on the auditory nerve which transmits sound information to the brain. This individual coding only occurs if the frequency components are different enough in frequency, otherwise they are in the same critical band and are coded at the same place and are perceived as one sound instead of two.Moore, B.C.J. (1986) Frequency Selectivity in Hearing, London, Academic Press The filters that distinguish one sound from another are called auditory filters, listening channels or critical bandwidths.

A bone-anchored hearing aid (BAHA) is a type of hearing aid based on bone conduction. It is primarily suited for people who have conductive hearing losses, unilateral hearing loss, single-sided deafness and people with mixed hearing losses who cannot otherwise wear 'in the ear' or 'behind the ear' hearing aids. They are more expensive than conventional hearing aids, and their placement involves invasive surgery which carries a risk of complications, although when complications do occur, they are usually minor. Two of the causes of hearing loss are lack of function in the inner ear (cochlea) and when the sound has problems in reaching the nerve cells of the inner ear.

The ossicles are a complex system of levers whose functions include: reducing the amplitude of the vibrations; increasing the mechanical force of vibrations; and thus improving the efficient transmission of sound energy from the eardrum to the inner ear structures. The ossicles act as the mechanical analog of an electrical transformer, matching the mechanical impedance of vibrations in air to vibrations in the liquid of the cochlea. The net effect of this impedance matching is to greatly increase the overall sensitivity and upper frequency limits of mammalian hearing, as compared to reptilian hearing. The details of these structures and their effects vary noticeably between different mammal species, even when the species are as closely related as humans and chimpanzees.

The vibrations of the endolymph in the cochlear duct displace the basilar membrane in a pattern that peaks a distance from the oval window depending upon the soundwave frequency. The organ of Corti vibrates due to outer hair cells further amplifying these vibrations. Inner hair cells are then displaced by the vibrations in the fluid, and depolarise by an influx of K+ via their tip- link-connected channels, and send their signals via neurotransmitter to the primary auditory neurons of the spiral ganglion. The hair cells in the organ of Corti are tuned to certain sound frequencies by way of their location in the cochlea, due to the degree of stiffness in the basilar membrane.

The upper frequency limit in humans (approximately 20 kHz) is due to limitations of the middle ear. Auditory sensation can occur if high‐intensity ultrasound is fed directly into the human skull and reaches the cochlea through bone conduction, without passing through the middle ear. Children can hear some high-pitched sounds that older adults cannot hear, because in humans the upper limit pitch of hearing tends to decrease with age. An American cell phone company has used this to create ring signals that supposedly are only audible to younger humans, but many older people can hear the signals, which may be because of the considerable variation of age-related deterioration in the upper hearing threshold.

Research has come to the consensus that AIED is the result of antibodies or other immune cells that cause damage to structures of the inner ear such as the cochlea and vestibular system. Of note, AIED is the only known SNHL that responds to medical treatment, but withholding treatment for longer than three months may result in permanent hearing loss and the need for cochlear implant installation. Although AIED has been studied extensively over the past 25 years, no clear mechanism of pathogenesis has emerged. A recent paper performed a literature review of all relevant articles dating back to 1980, and proposed a mechanism of pathogenesis which includes an inflammatory response and immune cell attack on inner ear structures.

A sensory space can also map into a particular region on an animal's body. For example, it could be a hair in the cochlea or a piece of skin, retina, or tongue or other part of an animal's body. This concept of receptive fields can be extended further up the nervous system; if many sensory receptors all form synapses with a single cell further up, they collectively form the receptive field of that cell. For example, the receptive field of a ganglion cell in the retina of the eye is composed of input from all of the photoreceptors which synapse with it, and a group of ganglion cells in turn forms the receptive field for a cell in the brain.

Onychonycteridae is an extinct family of bats known only from the early Eocene of Europe and North America. The type species, Onychonycteris finneyi, was described in 2008 from two nearly complete skeletons found in the Green River Formation of southwestern Wyoming. Since that time a number of previously described fossil bat species have been assigned to Onychonycteridae, as well as another more recently discovered species Most species belonging to Onychonycteridae are known only from isolated teeth and jaw fragments, however, they can be recognized by their relatively square-shaped upper molars, simple lower fourth premolar, and primitive, necromantodont lower molars. Onychonycteris finneyi exhibits additional primitive features of its skeleton, including claws on all five fingers and a simple cochlea that suggests it was incapable of echolocation.

This may have been used at first mainly to forage on the ground for insects and map out their surroundings in their gliding phase, or for communicative purposes. After the adaptation of flight was established, it may have been refined to target flying prey by echolocation. Bats may have evolved echolocation through a shared common ancestor, in which case it was then lost in the Old World megabats, only to be regained in the horseshoe bats; or, echolocation evolved independently in both the Yinpterochiroptera and Yangochiroptera lineages. Analyses of the hearing gene Prestin seem to favour the idea that echolocation developed independently at least twice, rather than being lost secondarily in the pteropodids, but ontogenic analysis of the cochlea supports that laryngeal echolocation evolved only once.

In 1977 the DRF funded research in outer ear hair cell motility that led to a new method for measuring the health of a newborn's ear, and began funding research to understand how sensory cells transmit sounds from the world to the brain. The DRF funded research led, in 1987, to the discovery of spontaneous regeneration of hair cells in chickens, thus igniting the field of hair cell regeneration in humans. Research on the regrowth of cochlea cells may lead to medical treatments that restore hearing. Unlike birds and reptiles, humans and other mammals are normally unable to regrow the cells of the inner ear that convert sound into neural signals when those cells are damaged by age or disease.

After a short postdoctoral research fellowship supervised by Abdus Salam at the International Centre for Theoretical Physics in Trieste, Italy he retrained as a physiologist at UCL, gaining a Master of Science degree in 1974 which led to work with Paul Fatt and Gertrude Falk between 1974 and 1977 in the Biophysics Department. Ashmore was appointed a Lecturer in Physiology at the University of Bristol in 1983 and promoted to Reader in 1988, before moving back to UCL in 1993. Ashmore has worked on dissecting the cellular mechanisms of hearing by studying the organ of Corti in the mammalian cochlea especially the guinea pig (Cavia porcellus). This structure in the inner ear increases the selectivity and sensitivity of our hearing through an in-built cochlear amplifier.

Earth pressure balance, or EPB, is a mechanised tunneling method in which the excavated material is used to support the tunnel face whilst it is being plasticised using foams/slurry & other additives to make it transportable and impermeable. The spoil is admitted into the tunnel boring machine (TBM) via a screw conveyor (cochlea) arrangement which allows the pressure at the face of the TBM to remain balanced without the use of slurry. This has allowed soft, wet, or unstable ground to be tunneled with a speed and safety not previously possible. The Channel Tunnel, the Thames Water Ring Main, sections of the London Underground, and most new metro tunnels completed in the last 20 years worldwide were excavated using this method.

Inner ear The initial triggers of Ménière's disease are not fully understood, with a variety of potential inflammatory causes that lead to endolymphatic hydrops (EH), a distension of the endolymphatic spaces in the inner ear. EH, in turn, is strongly associated with developing MD, but not everyone with EH develops MD: "The relationship between endolymphatic hydrops and Meniere's disease is not a simple, ideal correlation." Additionally, in fully developed MD the balance system (vestibular system) and the hearing system (cochlea) of the inner ear are affected, but there are cases where EH affects only one of the two systems enough to cause symptoms. The corresponding subtypes of MD are called vestibular MD, showing symptoms of vertigo, and cochlear MD, showing symptoms of hearing loss and tinnitus.

Uniporter channels open in response to a stimulus and allow the free flow of specific molecules. There are several ways in which the opening of uniporter channels may be regulated: # Voltage – Regulated by the difference in voltage across the membrane # Stress – Regulated by physical pressure on the transporter (as in the cochlea of the ear) # Ligand – Regulated by the binding of a ligand to either the intracellular or extracellular side of the cell Uniporters are involved in many biological processes, including action potentials in neurons. Voltage- gated sodium channels are involved in the propagation of a nerve impulse across the neuron. During transmission of the signal from one neuron to the next, calcium is transported into the presynaptic neuron by voltage-gated calcium channels.

As the above quotation shows, Müller's law seems to differ from the modern statement of the law in one key way. Müller attributed the quality of an experience to some specific quality of the energy in the nerves. For example, the visual experience from light shining into the eye, or from a poke in the eye, arises from some special quality of the energy carried by optic nerve, and the auditory experience from sound coming into the ear, or from electrical stimulation of the cochlea, arises from some different, special quality of the energy carried by the auditory nerve. In 1912, Lord Edgar Douglas Adrian showed that all neurons carry the same energy, electrical energy in the form of action potentials.

After the fork starts vibrating, placing it in the mouth with the stem between the back teeth ensures that one continues to hear the note via bone conduction, and both hands are free to do the tuning. Ludwig van Beethoven used bone conduction after losing most of his hearing, by placing one end of a rod in his mouth and resting the other end on the rim of his piano. It has also been observed that some animals can perceive sound and even communicate by sending and receiving vibration through bone. Comparison of hearing sensitivity through bone conduction and directly through the ear canal can aid audiologists in identifying pathologies of the middle ear—the area between the tympanic membrane (ear drum) and the cochlea (inner ear).

The mid frequency projections end up in between the two extremes; in this way the tonotopic organization that is established in the cochlea is preserved in the cochlear nuclei. This tonotopic organization is preserved because only a few inner hair cells synapse on the dendrites of a nerve cell in the spiral ganglion, and the axon from that nerve cell synapses on only a very few dendrites in the cochlear nucleus. In contrast with the VCN that receives all acoustic input from the auditory nerve, the DCN receives input not only from the auditory nerve but it also receives acoustic input from neurons in the VCN (T stellate cells). The DCN is therefore in a sense a second order sensory nucleus.

Immediately after the war, Hoyle and Bondi returned to Cambridge, while Gold stayed with naval research until 1947. He then began working at Cambridge's Cavendish Laboratory to help construct the world's largest magnetron, a device invented by two British scientists in 1940 that generated intense microwaves for radar. Soon after, Gold joined R. J. Pumphrey, a zoologist at the Cambridge Zoology Laboratory who had served as the deputy head of radar naval research during the war, to study the effect of resonance on the human ear. He found that the degree of resonance observed in the cochlea was not in accordance with the level of damping that would be expected from the viscosity of the watery liquid that fills the inner ear.

Owing to a limited literature on the subject, birds are believed to have very limited regenerative abilities as adults. Some studies on roosters have suggested that birds can adequately regenerate some parts of the limbs and depending on the conditions in which regeneration takes place, such as age of the animal, the inter-relationship of the injured tissue with other muscles, and the type of operation, can involve complete regeneration of some musculoskeletal structure. Werber and Goldschmidt (1909) found that the goose and duck were capable of regenerating their beaks after partial amputation and Sidorova (1962) observed liver regeneration via hypertrophy in roosters. Birds are also capable of regenerating the hair cells in their cochlea following noise damage or ototoxic drug damage.

Pure-tone audiometry only measures audibility thresholds, rather than other aspects of hearing such as sound localization and speech recognition. However, there are benefits to using pure-tone audiometry over other forms of hearing test, such as click auditory brainstem response (ABR). Pure-tone audiometry provides ear specific thresholds, and uses frequency specific pure tones to give place specific responses, so that the configuration of a hearing loss can be identified. As pure-tone audiometry uses both air and bone conduction audiometry, the type of loss can also be identified via the air-bone gap. Although pure-tone audiometry has many clinical benefits, it is not perfect at identifying all losses, such as ‘dead regions’ of the cochlea and neuropathies such as auditory processing disorder (APD).

There are two types of afferent neurons found in the cochlear nerve: Type I and Type II. Each type of neuron has specific cell selectivity within the cochlea. The mechanism that determines the selectivity of each type of neuron for a specific hair cell has been proposed by two diametrically opposed theories in neuroscience known as the peripheral instruction hypothesis and the cell autonomous instruction hypothesis. The peripheral instruction hypothesis states that phenotypic differentiation between the two neurons are not made until after these undifferentiated neurons attach to hair cells which in turn will dictate the differentiation pathway. The cell autonomous instruction hypothesis states that differentiation into Type I and Type II neurons occur following the last phase of mitotic division but preceding innervations.

However, for pre-lingually deaf children the risk of not acquiring spoken language even with an implant may be as high as 30%. One of the challenges that remain with these implants is that hearing and speech understanding skills after implantation show a wide range of variation across individual implant users. Factors such as duration and cause of hearing loss, how the implant is situated in the cochlea, the overall health of the cochlear nerve, but also individual capabilities of re-learning are considered to contribute to this variation, yet no certain predictive factors are known. Despite providing the ability for hearing and oral speech communication to children and adults with severe to profound hearing loss, there is also controversy around the devices.

Current work on this standard occurs primarily in the maintenance of IEC 60268, the international standard for sound systems. The CCIR curve differs greatly from A-weighting in the 5 to 8 kHz region where it peaks to +12.2 dB at 6.3 kHz, the region in which we appear to be extremely sensitive to noise. While it has been said (incorrectly) that the difference is due to a requirement for assessing noise intrusiveness in the presence of programme material, rather than just loudness, the BBC report makes clear the fact that this was not the basis of the experiments. The real reason for the difference probably relates to the way in which our ears analyse sounds in terms of spectral content along the cochlea.

When a person becomes blind or deaf they generally do not lose the ability to hear or see; they simply lose their ability to transmit the sensory signals from the periphery (retina for visions and cochlea for hearing) to brain. Since the vision processing pathways are still intact, a person who has lost the ability to retrieve data from the retina can still see subjective images by using data gathered from other sensory modalities such as touch or audition. In a regular visual system, the data collected by the retina is converted into an electrical stimulus in the optic nerve and relayed to the brain, which re-creates the image and perceives it. Because it is the brain that is responsible for the final perception, sensory substitution is possible.

These tiny, flexible electrodes are inserted into cochlea, and deliver electrical pulses along the nerve to transduce sound from the environment into signals that the brain can interpret. By creating machines that have physical properties that are compatible with biological tissues, Lacour is able to establish a communication link between the external world, the device, and the brain to enhance the quality of life for people suffering from hearing loss. In 2012, Lacour gave a talk at TEDxHelvetia discussing the use of silicon rubber as a substrate for electronic circuit construction, and the trick of combining these flexible materials with typical electronic conductive materials to enable electrical function. She deems this the “soft to hard challenge” - making electronic 3D structures that interface the most delicate tissues like nerves, spinal chords, and the brain.

The success of a cochlear implant relies in part upon electrode array placement within the cochlea in which the positioning is based on the frequency-spatial relationship empirically described by the Greenwood function. By aligning the electrodes with the positions of the auditory ganglia contacting the basilar membrane as described by the Greenwood function, the cochlear implant electrode array stimulates auditory ganglia associated with the reception of frequencies associated with speech recognition. Electrode array insertion depth is guided by the frequency map created by the Greenwood function, and allows electrical stimulation of neurons involved in stimulating the area of the brain responsible for speech recognition while minimizing ganglia stimulation in noise-generating regions. Well-placed electrode arrays in patients receiving cochlear implants can allow otherwise deafened auditory systems to achieve hearing and recognize speech.

The reason the ABR does not identify small tumors can be explained by the fact that ABRs rely on latency changes of peak V. Peak V is primarily influenced by high-frequency fibers, and tumors will be missed if those fibers aren't affected. Although the click stimulates a wide frequency region on the cochlea, phase cancellation of the lower-frequency responses occurs as a result of time delays along the basilar membrane. If a tumor is small, it is possible those fibers won't be sufficiently affected to be detected by the traditional ABR measure. Primary reasons why it is not practical to simply send every patient in for an MRI are the high cost of an MRI, its impact on patient comfort, and limited availability in rural areas and third-world countries.

Hearing is not a purely mechanical phenomenon of wave propagation, but is also a sensory and perceptual event; in other words, when a person hears something, that something arrives at the ear as a mechanical sound wave traveling through the air, but within the ear it is transformed into neural action potentials. The outer hair cells (OHC) of a mammalian cochlea give rise to an enhanced sensitivity and better frequency resolution of the mechanical response of the cochlear partition. These nerve pulses then travel to the brain where they are perceived. Hence, in many problems in acoustics, such as for audio processing, it is advantageous to take into account not just the mechanics of the environment, but also the fact that both the ear and the brain are involved in a person’s listening experience.

TRP channels are typically non-selective, although a few are selective for calcium or hydrated magnesium ions, and are composed of integral membrane proteins. Although many TRP channels are activated by voltage change, ligand binding, or temperature change, some TRP channels have been hypothesized to be involved in mechanotransduction. Some examples are TRPV4, which mediates mechanical load in a variety of tissues, including the liver, heart, lung, trachea, testis, spleen, salivary glands, cochlea, and vascular endothelial cells, as well as TRPC1 and TRPC6, which are involved in muscle mechanosensation. TRPC1 is expressed in the myocytes of the heart, arteries, and skeletal muscle. TRPC1 is widely considered to be a non- selective “store-operated ion channel” (SOC) involved in the calcium influx following calcium depletion of the endoplasmic reticulum of the cell.

A particular use of the term is physiological stimulation, which refers to sensory excitation, the action of various agents or forms of energy (stimuli) on receptors that generate impulses that travel through nerves to the brain (afferents). There are sensory receptors on or near the surface of the body, such as photoreceptors in the retina of the eye, hair cells in the cochlea of the ear, touch receptors in the skin and chemical receptors in the mouth and nasal cavity. There are also sensory receptors in the muscles, joints, digestive tract, and membranes around organs such as the brain, the abdominal cavity, the bladder and the prostate (providing one source of sexual stimulation). Stimulation to the external or internal senses may evoke involuntary activity or guide intentions in action.

The osseous spiral lamina is a bony shelf or ledge which projects from the modiolus into the interior of the canal, and, like the canal, takes two-and- three-quarter turns around the modiolus. It reaches about half-way toward the outer wall of the tube, and partially divides its cavity into two passages or scalae, of which the upper is named the scala vestibuli, while the lower is termed the scala tympani. Near the summit of the cochlea the lamina ends in a hook-shaped process, the hamulus laminae spiralis; this assists in forming the boundary of a small opening, the helicotrema, through which the two scalae communicate with each other. From the spiral canal of the modiolus numerous canals pass outward through the osseous spiral lamina as far as its free edge.

An outstanding example of the physician–humanist, Cotugno was devoted to books and accumulated a large library, was well versed in art, architecture, numismatics, and antiquities, and had a great facility in the Latin language. In 1761 Cotugno published for distribution to friends a plate that traced the course of the nasopalatine nerve, which is responsible for sneezing. Antonio Scarpa acknowledged his priority in knowledge of this nerve. In the same year his anatomical dissertation De aquaeductibus auris humane internae, following the work of Guichard Joseph Duverney and Antonio Maria Valsalva and anticipating that of Hermann von Helmholtz, described the vestibule, semicircular canals, and cochlea of the osseus labyrinth of the internal ear, demonstrated the existence of the labyrinthine fluid, and formulated a theory of resonance and hearing.

The company’s technology was built around the foundation of Computational Auditory Scene Analysis (CASA) -- a field of study that builds on the concept of Auditory Scene Analysis (ASA), a term first coined by psychologist Albert Bregman. ASA enables humans to accurately group sounds—even when composed of multiple frequencies, as in music, or when heard simultaneously –- and avoid blending "sources." As a result, ASA allows the listener to correctly distinguish and identify a sound of interest, like a voice, from other noise sources. CASA attempts to recreate sound source separation in the same manner as human hearing, but in machines. Using the principles of CASA, Audience’s earSmart processors act like a human cochlea and group different sounds, based on a diverse list of cues such as pitch, onset/offset time, spatial location and harmonicity.

Researchers interested in understanding the neurophysiological underpinnings of amblyaudia consider it to be a brain based hearing disorder that may be inherited or that may result from auditory deprivation during critical periods of brain development. Individuals with amblyaudia have normal hearing sensitivity (in other words they hear soft sounds) but have difficulty hearing in noisy environments like restaurants or classrooms. Even in quiet environments, individuals with amblyaudia may fail to understand what they are hearing, especially if the information is new or complicated. Amblyaudia can be conceptualized as the auditory analog of the better known central visual disorder amblyopia. The term “lazy ear” has been used to describe amblyaudia although it is currently not known whether it stems from deficits in the auditory periphery (middle ear or cochlea) or from other parts of the auditory system in the brain, or both.

This type of somatotopic map is the most common, possibly because it allows for physically neighboring areas of the brain to react to physically similar stimuli in the periphery or because it allows for greater motor control. The somatosensory cortex is adjacent to the primary motor cortex which is similarly mapped. Sensory maps may play an important role in facilitating motor responses. Other examples of sensory map organization may be that adjacent brain regions are related through proximity of the receptors that they process as in the map of the cochlea in the brain, or that similar features are processed as in the map of the feature detectors or the retinotopic map, or that time codes are used in organization as in the maps of an owl's sense of direction via interaural time difference between ears.

Although few studies have been done to link this to genes known to be involved in human Waardenburg syndrome, a syndrome of hearing loss and depigmentation caused by a genetic disruption to neural crest cell development, such a disruption would lead to this presentation in cats as well. Waardenburg syndrome type 2A (caused by a mutation in MITF) has been found in many other small mammals including dogs, minks and mice, and they all display at least patchy white depigmentation and some degeneration of the cochlea and saccule, as in deaf white cats. A major gene that causes a cat to have a white coat is a dominant masking gene, an allele of KIT which suppresses pigmentation and hearing. The cat would have an underlying coat colour and pattern, but when the dominant white gene is present, that pattern will not be expressed, and the cat will be deaf.

Hudspeth's research is focused on sensorineural hearing loss, and the deterioration of the hair cells, the sensory cells of the cochlea. Hudspeth's bold interpretation of the data obtained in his careful experimental research combined with biophysical modelling lead him to propose for the first time that the sense of hearing depends on a channel that is opened by mechanical force: The hair cells located in the inner ear perceive sound when their apical end -consisting of a bundle of filaments- bends in response to the movement caused by this sound. The activated hair cell rapidly fills with calcium entering from the outside of the cell, which in turn activates the release of neurotransmitters that start a signal to the brain. Hudspeth proposed the existence of a "gating spring" opened by direct mechanical force that would open an hypothetical channel responsible for the entry of calcium ions.

Duverney published one of the earliest comprehensive works on otology (Paris, 1683): Traité de l'organe de l'ouie, contenant la structure, les usages et les maladies de toutes les parties de l'oreille (Treatise on the organ of hearing, containing the structure, function, and diseases of all parts of the ear). In the book he discusses the anatomy, physiology and diseases associated with the ear. Duverney's theory of hearing (which he conceived with the help of physicist Edme Mariotte)Anthony F. Jahn, Joseph Santos-Sacchi, was fundamentally similar to what physiologist Hermann von Helmholtz (1821–1894) later proposed in the mid-19th century, except that he thought that high frequency would resonate near the apex of the cochlea, and low frequencies near the base (Domenico Cotugno had to turn this around in 1760). In 1683, Duverney identified a temporal bone tumor, which is believed to be the earliest description of cholesteatoma.

If the BC responses are normal, 0-24 dB HL, and the AC are worse than 25 dB HL, as well as a 10 dB gap between the air and bone responses, a conductive hearing loss is present. {updated March 2019} The modified Hughson–Westlake method is used by many audiologists during testing. A battery of (1) otoscopy, to view the ear canal and tympanic membrane, (2) tympanometry, to assess the immittance of the tympanic membrane and how well it moves, (3) otoacoustic emissions, to measure the response of the outer hair cells located in the cochlea, (4) audiobooth pure-tone testing, to obtain thresholds to determine the type, severity, and pathology of the hearing loss present, and (5) speech tests, to measure the patients recognition and ability to repeat the speech heard, is all taken into consideration when diagnosing the pathology of the patient.

Normally, vibrations of the tympanic membrane (eardrum) elicited by acoustic stimuli are transmitted through the chain of ossicles (malleus, incus, and stapes) in the middle ear to the oval window of the cochlea. Vibrations of the footplate of stapes transmit through the oval window to the perilymph, which in turn causes the endolymph, the basilar membrane, and the organ of Corti to vibrate, activating ultimately the acoustic sensor cells, the inner hair cells of the organ of Corti. The transfer function of this complex mechanical system under physiological conditions is modulated by the action of two small muscles of the middle ear, the tensor tympani, and stapedius. The tensor tympani arises from the cartilaginous portion of the auditory tube and the osseous canal of the sphenoid and, having sharply bent over the extremity of the septum, attaches to the manubrium of the malleus (hammer); its contraction pulls the malleus medially, away from the tympanic membrane, which tenses the membrane.

Both studies showed that the hearing loss sustained by animals due to binaural sound exposure was more severe if the OCB was severed. Rajan (1995b) also showed a frequency dependence of MOC protection roughly consistent with the distribution of MOC fibres in the cochlea. Other studies supporting this function of the MOCS have shown that MOC stimulation reduces the temporary threshold shift (TTS) and permanent threshold shift (PTS) associated with prolonged noise exposure (Handrock and Zeisberg, 1982; Rajan, 1988b; Reiter and Liberman, 1995), and that animals with the strongest MOC reflex sustain less hearing damage to loud sounds (Maison and Liberman, 2000). This proposed biological role of the MOCS, protection from loud sounds, was challenged by Kirk and Smith (2003), who argued that the intensity of sounds used in the experiments (≥105 dB SPL) would rarely or never occur in nature, and therefore a protective mechanism for sounds of such intensities could not have evolved.

From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the utriculosaccular duct, and then passes along the vestibular aqueduct and ends in a blind pouch, the endolymphatic sac, on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater. Studies suggest that the endolymphatic duct and endolymphatic sac perform both absorptive and secretory,Schuknecht HF. Pathology of the Ear. Philadelphia, Pa: Lea & Febiger; 1993:45–47, 50–51, 62, 64, 101Wackym PA, Friberg U, Bagger-Sjo¨ba¨ck D, Linthicum FH Jr, Friedmann I, Rask-Andersen H. Human endolymphatic sac: possible mechanisms of pressure regulation. J Laryngol Otol 1987; 101:768–779Yeo SW, Gottschlich S, Harris JP, Keithley EM. Antigen diffusion from the perilymphatic space of the cochlea. Laryngoscope 1995; 105:623–628Rask-Andersen H, Danckwardt-Lilliestrom N, Linthicum FH, House WF. Ultrastructural evidence of a merocrine secretion in the human endolymphatic sac.

Auditory response to transmitted frequencies from approximately 200 MHz to at least 3 GHz has been reported. The cause is thought to be thermoelastic expansion of portions of auditory apparatus, and the generally accepted mechanism is rapid (but minuscule, in the range of 10−5 °C) heating of brain by each pulse, and the resulting pressure wave traveling through the skull to the cochlea. In 1975, an article by neuropsychologist Don Justesen discussing radiation effects on human perceptions referred to an experiment by Joseph C. Sharp and Mark Grove at the Walter Reed Army Institute of Research during which Sharp and Grove reportedly were able to recognize nine out of ten words transmitted by "voice modulated microwaves". Since the radiation levels approached the (then current) 10 mW/cm² limit of safe exposure, critics have observed that under such conditions brain damage from thermal effects of high power microwave radiation would occur, and there was "no conclusive evidence for MAE at lower energy densities".

However, it has long been noted that a neural mechanism that may accomplish a delay—a necessary operation of a true autocorrelation—has not been found. At least one model shows that a temporal delay is unnecessary to produce an autocorrelation model of pitch perception, appealing to phase shifts between cochlear filters; however, earlier work has shown that certain sounds with a prominent peak in their autocorrelation function do not elicit a corresponding pitch percept, and that certain sounds without a peak in their autocorrelation function nevertheless elicit a pitch. To be a more complete model, autocorrelation must therefore apply to signals that represent the output of the cochlea, as via auditory-nerve interspike-interval histograms. Some theories of pitch perception hold that pitch has inherent octave ambiguities, and therefore is best decomposed into a pitch chroma, a periodic value around the octave, like the note names in western music—and a pitch height, which may be ambiguous, that indicates the octave the pitch is in.

The perception model of ENV processing that incorporates selective (bandpass) AM filters accounts for many perceptual consequences of cochlear dysfunction including enhanced sensitivity to AM for sinusoidal and noise carriers, abnormal forward masking (the rate of recovery from forward masking being generally slower than normal for impaired listeners), stronger interference effects between AM and FM and enhanced temporal integration of AM. The model of Torsten Dau has been extended to account for the discrimination of complex AM patterns by hearing-impaired individuals and the effects of noise-reduction systems. The performance of the hearing-impaired individuals was best captured when the model combined the loss of peripheral amplitude compression resulting from the loss of the active mechanism in the cochlea with an increase in internal noise in the ENVn domain. Phenomenological models simulating the response of the peripheral auditory system showed that impaired AM sensitivity in individuals experiencing chronic tinnitus with clinically normal audiograms could be predicted by substantial loss of auditory-nerve fibers with low spontaneous rates and some loss of auditory-nerve fibers with high-spontaneous rates.

Moore was one of the first researchers to present convincing evidence for the role of phase locking (the synchronization of nerve spikes to individual cycles of the filtered stimulus in the cochlea) in the perception of pitch. He showed that the ability of human listeners to detect small changes in frequency of brief tones was too good to be accounted for by a place mechanism of pitch for frequencies up to about 4 kHz. Together with Stephan Ernst he later showed that the ability to detect small changes in frequency worsened with increasing frequency from 2 to 8 kHz, consistent with the roll-off in the precision of phase-locking information at high frequencies, and then reached a plateau, consistent with a transition to a place mechanism. Together with Aleksander Sek he showed that phase locking to the temporal fine structure of complex tones contributes to the perception of pitch up to higher frequencies than previously assumed and that the detection of frequency modulation for low modulation rates also probably depends on phase locking.