Dynamics of cochlear nonlinearity: Automatic gain control or instantaneous damping?

Alessandro Altoè, Karolina K. Charaziak, Christopher A. Shera

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)
    72 Downloads (Pure)


    Measurements of basilar-membrane (BM) motion show that the compressive nonlinearity of cochlear mechanical responses is not an instantaneous phenomenon. For this reason, the cochlear amplifier has been thought to incorporate an automatic gain control (AGC) mechanism characterized by a finite reaction time. This paper studies the effect of instantaneous nonlinear damping on the responses of oscillatory systems. The principal results are that (i) instantaneous nonlinear damping produces a noninstantaneous gain control that differs markedly from typical AGC strategies; (ii) the kinetics of compressive nonlinearity implied by the finite reaction time of an AGC system appear inconsistent with the nonlinear dynamics measured on the gerbil basilar membrane; and (iii) conversely, those nonlinear dynamics can be reproduced using an harmonic oscillator with instantaneous nonlinear damping. Furthermore, existing cochlear models that include instantaneous gain-control mechanisms capture the principal kinetics of BM nonlinearity. Thus, an AGC system with finite reaction time appears neither necessary nor sufficient to explain nonlinear gain control in the cochlea.

    Original languageEnglish
    Pages (from-to)3510-3519
    Number of pages10
    JournalJournal of the Acoustical Society of America
    Issue number6
    Publication statusPublished - 1 Dec 2017
    MoE publication typeA1 Journal article-refereed


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