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Some effects of spatial randomness along the length of the cochlear on its performance

Some effects of spatial randomness along the length of the cochlear on its performance
Some effects of spatial randomness along the length of the cochlear on its performance
If the active cochlear is modelled as having a uniform distribution of parameters, the system is stable even for high gains in the cochlear amplifiers, resulting in very significant active enhancements of its response, of the order of 90 dB. In a real biological system, however, such uniform distributions will always be disrupted by random spatial variations, and a state space model of the cochlea has been developed that can be used to investigate the effects of such random variations. One effect is found to be that the cochlear amplifier gains have to be reduced to maintain stability, so that maximum active enhancements of the cochlear response is more typically 40 dB. The cochlear amplifier, however, is nonlinear as well as active, and unstable poles in the linear model generate instabilities that settle into limit cycle oscillations at discrete frequencies in the nonlinear model. These oscillations are thought to be the origin of spontaneous otoacoustic emissions, and have a significant effect on sound detection at low level. At higher sound pressure levels the nonlinearity in the cochlear amplifier suppresses such oscillations and the sound detection has a more uniform frequency response, although the amplification is reduced.
0001-4966
p.3192
Elliott, Stephen
721dc55c-8c3e-4895-b9c4-82f62abd3567
Ku, Emery
887d24a3-14dc-4a4c-beb2-eb0efae56317
Lineton, Ben
1ace4e96-34da-4fc4-bc17-a1d82b2ba0e2
Elliott, Stephen
721dc55c-8c3e-4895-b9c4-82f62abd3567
Ku, Emery
887d24a3-14dc-4a4c-beb2-eb0efae56317
Lineton, Ben
1ace4e96-34da-4fc4-bc17-a1d82b2ba0e2

Elliott, Stephen, Ku, Emery and Lineton, Ben (2007) Some effects of spatial randomness along the length of the cochlear on its performance. Journal of the Acoustical Society of America, 121 (5), p.3192.

Record type: Article

Abstract

If the active cochlear is modelled as having a uniform distribution of parameters, the system is stable even for high gains in the cochlear amplifiers, resulting in very significant active enhancements of its response, of the order of 90 dB. In a real biological system, however, such uniform distributions will always be disrupted by random spatial variations, and a state space model of the cochlea has been developed that can be used to investigate the effects of such random variations. One effect is found to be that the cochlear amplifier gains have to be reduced to maintain stability, so that maximum active enhancements of the cochlear response is more typically 40 dB. The cochlear amplifier, however, is nonlinear as well as active, and unstable poles in the linear model generate instabilities that settle into limit cycle oscillations at discrete frequencies in the nonlinear model. These oscillations are thought to be the origin of spontaneous otoacoustic emissions, and have a significant effect on sound detection at low level. At higher sound pressure levels the nonlinearity in the cochlear amplifier suppresses such oscillations and the sound detection has a more uniform frequency response, although the amplification is reduced.

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Published date: May 2007

Identifiers

Local EPrints ID: 50423
URI: http://eprints.soton.ac.uk/id/eprint/50423
ISSN: 0001-4966
PURE UUID: e0058f45-88a6-4787-b02b-090b62f34d7f
ORCID for Ben Lineton: ORCID iD orcid.org/0000-0003-4784-7762

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Date deposited: 26 Feb 2008
Last modified: 12 Sep 2022 01:38

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Contributors

Author: Stephen Elliott
Author: Emery Ku
Author: Ben Lineton ORCID iD

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