Modelling cochlear micromechanics
Modelling cochlear micromechanics
An active mechanism, the cochlear amplifier, enhances the response of the cochlea to low-level stimuli and is assumed to be controlled by the action of the outer hair cells (OHCs) located within the organ of Corti.
Classical models of the cochlea use an array of isolated lumped parameter systems along its length, coupled through the cochlear fluid. These models employ active feedback loops between the basilar and tectorial membrane (TM) for the mechanism of the cochlear amplifier. Several such models are reviewed and their underlying dynamic behaviour examined, in order to compare the predicted response with recent measurements of the relative motion within the organ of Corti. Their stability is also tested to establish reliability of calculated frequency responses. The models are conditionally stable and operate close to instability to achieve high sensitivity of the cochlear amplifier. Compressive nonlinearity is also included in one of the classical models using a quasi-linear approach.
It has recently been suggested that wave motion within the organ of Corti may also play a role in the cochlear amplifier. The behaviour of two possible types of wave between the reticular lamina and the TM is examined, one in which the TM is assumed to behave as a plate in bending and another in which it is assumed to behave like an elastic half-space. The propagation speed is very low for both waves and incorporation of the losses induced by viscosity causes the waves to decay significantly within a wavelength. Feedback from the OHCs coupled into these waves outcomes the effects of viscosity and enhances waves’ resonant supporting this form of amplification in the cochlea.
University of Southampton
Pierzycki, Robert Henryk
0807f657-2b16-48f1-adfa-4d6126cf9479
2007
Pierzycki, Robert Henryk
0807f657-2b16-48f1-adfa-4d6126cf9479
Pierzycki, Robert Henryk
(2007)
Modelling cochlear micromechanics.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
An active mechanism, the cochlear amplifier, enhances the response of the cochlea to low-level stimuli and is assumed to be controlled by the action of the outer hair cells (OHCs) located within the organ of Corti.
Classical models of the cochlea use an array of isolated lumped parameter systems along its length, coupled through the cochlear fluid. These models employ active feedback loops between the basilar and tectorial membrane (TM) for the mechanism of the cochlear amplifier. Several such models are reviewed and their underlying dynamic behaviour examined, in order to compare the predicted response with recent measurements of the relative motion within the organ of Corti. Their stability is also tested to establish reliability of calculated frequency responses. The models are conditionally stable and operate close to instability to achieve high sensitivity of the cochlear amplifier. Compressive nonlinearity is also included in one of the classical models using a quasi-linear approach.
It has recently been suggested that wave motion within the organ of Corti may also play a role in the cochlear amplifier. The behaviour of two possible types of wave between the reticular lamina and the TM is examined, one in which the TM is assumed to behave as a plate in bending and another in which it is assumed to behave like an elastic half-space. The propagation speed is very low for both waves and incorporation of the losses induced by viscosity causes the waves to decay significantly within a wavelength. Feedback from the OHCs coupled into these waves outcomes the effects of viscosity and enhances waves’ resonant supporting this form of amplification in the cochlea.
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Published date: 2007
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Local EPrints ID: 466272
URI: http://eprints.soton.ac.uk/id/eprint/466272
PURE UUID: 0cba9596-a427-4cfb-af07-91c0f2b7993e
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Date deposited: 05 Jul 2022 05:00
Last modified: 16 Mar 2024 20:36
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Author:
Robert Henryk Pierzycki
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