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Testing a Model of Stimulus Frequency Otoacoustic Emissions in Humans

Testing a Model of Stimulus Frequency Otoacoustic Emissions in Humans
Testing a Model of Stimulus Frequency Otoacoustic Emissions in Humans

In recent theories of cochlear mechanics, it has been proposed that spontaneous, transiently evoked and stimulus frequency otoacoustic emissions originate from scattering of a "tall and broad" travelling wave (TW) with a random spatial distribution of cochlear inhomogeneities.

In the first theory, the periodicity is determined predominantly by the wavelength of the TW near its peak amplitude, whilst in the second it is determined by the spatial period of the corrugations, and is therefore largely independent of TW wavelength. The aim of this thesis is to test these two rival theories in humans by attempting to induce changes in the TW wavelength through ipsilateral acoustic suppression, whilst measuring any accompanying changes in the periodicity of stimulus frequency otoacoustic emissions (SFOAE).

For both theories, a one-dimensional longwave model of cochlear mechanics was developed including representations of the two scattering mechanisms and of nonlinear cochlear active processes. Detailed predictions of the changes in SFOAE periodicity under conditions of self-suppression and high-side, two-tone suppression were then made from both models. In the model with random inhomogeneities, the periodicity clearly increased with the extent of self-suppression, and decreased with the extent of two-tone suppression. In sharp contrast, in the model with regular spatial corrugations, no change in periodicity occurred in either case.

SFOAE periodicity generally increased with the extent of self-suppression and decreased with the extent of high-side, two-tone suppression. This result was interpreted as strong evidence favouring the theory of spatially random inhomogeneities over the rival theory of regular spatial corrugations, thereby enhancing understanding of the mechanism for generation of otoacoustic emissions.

University of Southampton
Lineton, Benjamin
d63c06a6-7f7b-4059-98c0-58759520b79f
Lineton, Benjamin
d63c06a6-7f7b-4059-98c0-58759520b79f

Lineton, Benjamin (2001) Testing a Model of Stimulus Frequency Otoacoustic Emissions in Humans. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

In recent theories of cochlear mechanics, it has been proposed that spontaneous, transiently evoked and stimulus frequency otoacoustic emissions originate from scattering of a "tall and broad" travelling wave (TW) with a random spatial distribution of cochlear inhomogeneities.

In the first theory, the periodicity is determined predominantly by the wavelength of the TW near its peak amplitude, whilst in the second it is determined by the spatial period of the corrugations, and is therefore largely independent of TW wavelength. The aim of this thesis is to test these two rival theories in humans by attempting to induce changes in the TW wavelength through ipsilateral acoustic suppression, whilst measuring any accompanying changes in the periodicity of stimulus frequency otoacoustic emissions (SFOAE).

For both theories, a one-dimensional longwave model of cochlear mechanics was developed including representations of the two scattering mechanisms and of nonlinear cochlear active processes. Detailed predictions of the changes in SFOAE periodicity under conditions of self-suppression and high-side, two-tone suppression were then made from both models. In the model with random inhomogeneities, the periodicity clearly increased with the extent of self-suppression, and decreased with the extent of two-tone suppression. In sharp contrast, in the model with regular spatial corrugations, no change in periodicity occurred in either case.

SFOAE periodicity generally increased with the extent of self-suppression and decreased with the extent of high-side, two-tone suppression. This result was interpreted as strong evidence favouring the theory of spatially random inhomogeneities over the rival theory of regular spatial corrugations, thereby enhancing understanding of the mechanism for generation of otoacoustic emissions.

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Published date: 2001

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Local EPrints ID: 464471
URI: http://eprints.soton.ac.uk/id/eprint/464471
PURE UUID: 99ec6a79-4bdb-4c2c-91d8-cc66507be9f8

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Date deposited: 04 Jul 2022 23:40
Last modified: 16 Mar 2024 19:32

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Author: Benjamin Lineton

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