Negative-delay sources in distortion product otoacoustic emissions.

Negative-delay sources in distortion product otoacoustic emissions.
Hear Res. 2017 Dec 22;:
Authors: Sisto R, Shera CA, Moleti A
Abstract
Long-delay components showing a symmetrical pattern with positive and negative delays can be observed in the time-frequency representation (or in the inverse Fourier transform) of distortion product otoacoustic emissions. Positive-only phase-gradient delays are predicted by place-fixed backscattering mechanisms, such as coherent reflection due to roughness, whereas the nonlinear distortion wave-fixed mechanism should generate an almost null-delay component. The symmetrical delay pattern arises whenever spectral amplitude fluctuations are not fully correlated to phase fluctuations. An interpretation of this phenomenon is proposed, involving place-fixed modulation of the spectral strength of the wave-fixed nonlinear generator. Experimental data are shown in which these negative-delay sources are particularly strong, and further amplified by contralateral stimulation, suggesting that this effect could be dynamically enhanced. Analytical solutions of a linear 1-d transmission line model, in which cubic nonlinearity and roughness were added as small perturbations, have been used to test this hypothesis.
PMID: 29287918 [PubMed - as supplied by publisher]

Source: Hearing Research - December 22, 2017 Category: Audiology Authors: Sisto R, Shera CA, Moleti A Tags: Hear Res Source Type: research