The role of tectorial membrane stiffness and viscosity on traveling waves and resonance

Shirin Farrahi, Jonathan B. Sellon, Roozbeh Ghaffari, Dennis M. Freeman

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Classical cochlear models have long suggested that the tectorial membrane (TM) is a resonant system, which contributes to both sensitivity and frequency selectivity. However, these models do not consider longitudinal coupling through the TM and assume damping in the subtectorial space controls sharpness of tuning. Recent TM wave motion results show that the TM can couple activity over several hundred rows of hair cells, suggesting that TM inertial and viscoelastic properties may overcome the dissipative effects of subtectorial damping. Here we manipulate the dynamic shear modulus (G′) and shear viscosity (η) of the TM by altering pH and adding polyethylene glycol (PEG) to the bath surrounding the TM. Analysis of a distributed impedance model shows that increasing TM shear viscosity (via addition of PEG) and decreasing shear modulus (via altering bath pH) both decrease wave decay constants by 35-42% over a broad range of frequencies. This reduction in spatial extent of TM waves is consistent with sharpened cochlear tuning (i.e. reduced spread of excitation), suggesting that TM wave and resonance models differ significantly. While both suggest that the TM plays an important role in determining cochlear tuning, the mechanism by which sharpened tuning is achieved in TM wave models is driven by spatial extent of TM waves.

    Original languageEnglish (US)
    Title of host publicationMechanics of Hearing
    Subtitle of host publicationProtein to Perception - Proceedings of the 12th International Workshop on the Mechanics of Hearing
    EditorsDavid P. Corey, K. Domenica Karavitaki
    PublisherAmerican Institute of Physics Inc.
    Volume1703
    ISBN (Electronic)9780735413504
    DOIs
    StatePublished - Dec 31 2015
    Event12th International Workshop on the Mechanics of Hearing: Protein to Perception - Cape Sounio, Greece
    Duration: Jun 23 2014Jun 29 2014

    Other

    Other12th International Workshop on the Mechanics of Hearing: Protein to Perception
    CountryGreece
    CityCape Sounio
    Period6/23/146/29/14

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

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