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

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Farrahi, S., Sellon, J. B., Ghaffari, R., & Freeman, D. M. (2015). The role of tectorial membrane stiffness and viscosity on traveling waves and resonance. In D. P. Corey, & K. D. Karavitaki (Eds.), Mechanics of Hearing: Protein to Perception - Proceedings of the 12th International Workshop on the Mechanics of Hearing (Vol. 1703). [080007] American Institute of Physics Inc.. https://doi.org/10.1063/1.4939398