Nonlinear dynamics of the mammalian inner ear

TL;DR

This paper introduces a nonlinear transmission-line model of the cochlea that explains neural tuning, spontaneous otoacoustic emissions, and their complex behaviors, challenging existing theories about cochlear resonances and emission origins.

Contribution

It presents a novel nonlinear model of the cochlea that accounts for SOAEs and their chaotic dynamics, providing new insights into cochlear mechanics and neural responses.

Findings

Middle ear has minimal effect on cochlear resonances

SOAEs originate from Hopf bifurcations, not localized instabilities

Emissions can exhibit chaotic, intermittent, and fragile behaviors

Abstract

A simple nonlinear transmission-line model of the cochlea with longitudinal coupling is introduced that can reproduce Basilar membrane response and neural tuning in the chinchilla. It is found that the middle ear has little effect on cochlear resonances, and hence conclude that the theory of coherent reflections is not applicable to the model. The model also provides an explanation of the emergence of spontaneous otoacoustic emissions (SOAEs). It is argued that SOAEs arise from Hopf bifurcations of the transmission-line model and not from localized instabilities. The paper shows that emissions can become chaotic, intermittent and fragile to perturbations.