Limit cycle oscillations in a nonlinear state space model of the human cochlea

Ku, Emery M., Elliott, Stephen J. and Lineton, Ben (2009) Limit cycle oscillations in a nonlinear state space model of the human cochlea. Journal of the Acoustical Society of America, 126 (2), 739-750. (doi:10.1121/1.3158861).

Abstract

It is somewhat surprising that linear analysis can account for so many features of the cochlea when it is inherently nonlinear. For example, the commonly detected spacing between adjacent spontaneous otoacoustic emissions (SOAEs) is often explained by a linear theory of “coherent reflection” [Zweig and Shera (1995). J. Acoust. Soc. Am. 98, 2018–2047]. The nonlinear saturation of the cochlear amplifier is, however, believed to be responsible for stabilizing the amplitude of a SOAE. In this investigation, a state space model is used to first predict the linear instabilities that arise, given distributions of cochlear inhomogeneities, and then subsequently to simulate the time-varying spectra of the nonlinear models. By comparing nonlinear simulation results to linear predictions, it is demonstrated that nonlinear effects can have a strong impact on the steady-state response of an unstable cochlear model. Sharply tuned components that decay away exponentially within 100 ms are shown to be due to linearly resonant modes of the model generated by the cochlear inhomogeneities. Some oscillations at linearly unstable frequencies are suppressed over a longer time scale, whereas those that persist are due to linear instabilities and their distortion products.

This record has no associated files available for download.

Contributors

Author: Ben Lineton

Download statistics