Modes and waves in a cochlear model

Chadwick, Richard S.; Fourney, M. E.; Neiswander, P.

doi:10.1016/0378-5955(80)90084-2

Cited by 13 publications

(6 citation statements)

References 4 publications

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“…This type of dependence, which has been predicted earlier in phenomenological models (Engebretson and Eldredge, 1968) and recently demonstrated experimentally There is at present a considerable variety of views about the nature and extent of nonlinearities in basilar membrane motion and fluid-cilia coupling mechanisms (Chadwick et al, 1980;Evans, 1975;Holton and Weiss, 1983a, b;Kim and Molnar, 1975;Palmer and Evans, 1980;Patuzzi and Sellick, 1983;Rhode, 1971;Sellick et al, 1983;Transcripts, 1980). We have elected to use a linear basilar membrane model since it affords a great deal of mathematical tractability and physiological relevance without sacrificing the major observed qualitative features of basilar membrane motion ( Chadwick et al, 1980). Nonlinear mechanisms for the generation of hair cell potentials and nerve spike trains, considered here and in other theoretical studies (Engebretson and Eldredge, 1968;Pfeitfer, 1970;Schroeder and Hall, 1974) have been shown capable of accounting for the various nonlinear phenomena such as two-tone suppression, saturation, and rectification.…”

Section: (B) ] and Can Be Traced To The Combined Influences Of The Nomentioning

confidence: 84%

A biophysical model of cochlear processing: Intensity dependence of pure tone responses

et al. 1986

The Journal of the Acoustical Society of America

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A mathematical model of cochlear processing is developed to account for the nonlinear dependence of frequency selectivity on intensity in inner hair cell and auditory nerve fiber responses. The model describes the transformation from acoustic stimulus to intracellular hair cell potentials in the cochlea. It incorporates a linear formulation of basilar membrane mechanics and subtectorial fluid-cilia displacement coupling, and a simplified description of the inner hair cell nonlinear transduction process. The analysis at this stage is restricted to low-frequency single tones. The computed responses to single tone inputs exhibit the experimentally observed nonlinear effects of increasing intensity such as the increase in the bandwidth of frequency selectivity and the downward shift of the best frequency. In the model, the first effect is primarily due to the saturating effect of the hair cell nonlinearity. The second results from the combined effects of both the nonlinearity and of the inner hair cell low-pass transfer function. In contrast to these shifts along the frequency axis, the model does not exhibit intensity dependent shifts of the spatial location along the cochlea of the peak response for a given single tone. The observed shifts therefore do not contradict an intensity invariant tonotopic code.

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Section: (B) ] and Can Be Traced To The Combined Influences Of The Nomentioning

confidence: 84%

A biophysical model of cochlear processing: Intensity dependence of pure tone responses

et al. 1986

The Journal of the Acoustical Society of America

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“…Studies by von Békésy (4,5) showing traveling waves in the basilar membrane using cochleae from cadavers led to the development of several physical models of the cochlea. The first group of these models comprised scaled-up versions of the cochlea (22)(23)(24). Recently, researchers have developed fluid-filled microscale models that respond to sound in a manner similar to the mammalian cochlea.…”

Section: Generation Of Voltage Output By the Implanted Device In Respmentioning

confidence: 99%

Piezoelectric materials mimic the function of the cochlear sensory epithelium

Inaoka

Shintaku²,

Nakagawa³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

123

127

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Cochlear hair cells convert sound vibration into electrical potential, and loss of these cells diminishes auditory function. In response to mechanical stimuli, piezoelectric materials generate electricity, suggesting that they could be used in place of hair cells to create an artificial cochlear epithelium. Here, we report that a piezoelectric membrane generated electrical potentials in response to sound stimuli that were able to induce auditory brainstem responses in deafened guinea pigs, indicating its capacity to mimic basilar membrane function. In addition, sound stimuli were transmitted through the external auditory canal to a piezoelectric membrane implanted in the cochlea, inducing it to vibrate. The application of sound to the middle ear ossicle induced voltage output from the implanted piezoelectric membrane. These findings establish the fundamental principles for the development of hearing devices using piezoelectric materials, although there are many problems to be overcome before practical application.cochlear implant | hearing loss | mechanoelectrical transduction | traveling wave | regeneration T he cochlea is responsible for auditory signal transduction in the auditory system. It responds to sound-induced vibrations and converts these mechanical signals into electrical impulses, which stimulate the auditory primary neurons. The human cochlea operates over a three-decade frequency band from 20 Hz to 20 kHz, covers a 120-dB dynamic range, and can distinguish tones that differ by <0.5% in frequency (1). It is relatively small, occupying a volume of <1 cm 3 , and it requires ∼14 μW power to function (2). The mammalian ear is composed of three parts: the outer, middle, and inner ears (Fig. 1A) (3). The outer ear collects sound and funnels it through the external auditory canal to the tympanic membrane. The cochlea consists of three compartments: scala vestibuli and scala tympani, which are filled with perilymph fluid, and scala media, which is filled with endolymph fluid (Fig. 1C). The scala vestibuli and scala tympani form a continuous duct that opens onto the middle ear through the oval and round windows. The stapes, an ossicle in the middle ear, is directly coupled to the oval window. Sound vibration is transmitted from the ossicles to the cochlear fluids through the oval window as a pressure wave that travels from the base to the apex of the scala vestibuli through the scala tympani and finally to the round window (Fig. 1B). The scala media are membranous ducts that are separated from the scala vestibuli by Reissner's membrane and separated from the scala tympani by the basilar membrane. The pressure wave propagated by the vibration of the stapes footplate causes oscillatory motion of the basilar membrane, where the organ of Corti is located. The organ of Corti contains the sensory cells of the auditory system; they are known as hair cells, because tufts of stereocilia protrude from their apical surfaces (Fig. 1D). The oscillatory motion of the basilar membrane results in the shear motion of the st...

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“…Helle's (4) model is seven times life size and exhibits tonotopic structure in the 25-to 800-Hz band. Chadwick et al (5) built a 24 times life-size model and clearly show strong standing wave patterns and the resulting discrete resonances. Because of the standing wave nature of their response, a tonotopic map is not demonstrated (5).…”

mentioning

confidence: 99%

Microengineered hydromechanical cochlear model

White

Grosh

2005

Proc. Natl. Acad. Sci. U.S.A.

100

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Micromachined fluid-filled variable impedance waveguides intended to mimic the mechanics of the passive mammalian cochlea have been fabricated and experimentally examined. The structures were microfabricated with dimensions similar to those of the biological system. Experimental tests demonstrate acoustically excited traveling fluid-structure waves with phase accumulations between 1.5 and 3 radians at the location of maximum response. The resulting measured frequency-position mapping function, with similarities to that observed in the cochlea, is presented. Results for both isotropic and orthotropic membranes are reported, demonstrating that the achieved orthotropy ratio of 8:1 in tension is insufficient to produce the sharp filtering observed in animal experiments and many computational models that use higher ratios. It is also shown experimentally that high viscosity fluids must be used to provide sufficient damping to avoid the formation of a nonphysiological standing wave pattern. A mathematical model incorporating a thin-layer viscous, compressible fluid approximation coupled to an orthotropic membrane model is validated against experimental results. The work presented herein is motivated by the possibility of producing microfabricated cochlear-like filters, thus the structure is designed for production in a scalable microfabrication process.acoustic ͉ micro-electro-mechanical systems ͉ sensor ͉ viscosity T he cochlea is the organ in the inner part of the mammalian ear that is responsible for the transduction of acoustic signals into neurological signals. The typical human cochlea operates over a 3-decade frequency band, from 20 Hz to 20 kHz, covers 120 dB of dynamic range, and can distinguish tones that differ by Ͻ0.5% (1). The cochlea is also very small, occupying a volume of Ϸ1 cm 3 . Perhaps most importantly, the cochlea uses a mechanical process to separate audio signals into Ϸ3,500 channels of frequency information. Thus, the cochlea is a sensitive real-time mechanical frequency analyzer.The effectiveness of the cochlea as a time-frequency analyzer motivates our efforts to construct a hydromechanical analog that can be fabricated repeatably and in a batch fashion. Integration of sensing elements with the mechanical structure would result in a combined acoustic sensor͞filter with a unique operating modality. During the design of the mechanical structure, we also learn more about some aspects of the biological cochlea. von Békésy's (2, 3) observation of traveling waves on the basilar membrane (BM) of cadaver cochleae motivated the construction of a number of physical models of the cochlea. The first group of these models involved scaled-up versions of the cochlea. Helle's (4) model is seven times life size and exhibits tonotopic structure in the 25-to 800-Hz band. Chadwick et al. (5) built a 24 times life-size model and clearly show strong standing wave patterns and the resulting discrete resonances. Because of the standing wave nature of their response, a tonotopic map is not demonstrated (5). Lechner'...

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Modes and waves in a cochlear model

Cited by 13 publications

References 4 publications

A biophysical model of cochlear processing: Intensity dependence of pure tone responses

A biophysical model of cochlear processing: Intensity dependence of pure tone responses

Piezoelectric materials mimic the function of the cochlear sensory epithelium

Microengineered hydromechanical cochlear model

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