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The Center for Control, Dynamical Systems, and Computation University of California at Santa Barbara
 

Summary: The Center for Control, Dynamical Systems, and Computation
University of California at Santa Barbara
Winter 2010 Seminar Series
Presents
Origins of the Compressive Nonlinearity of Hearing
Robert Szalai
University of Bristol
Friday, February 5, 2010, 3:00 ­ 4:00pm CHEM 1171
Abstract:
Mammalian hearing has a complex physiology that is still not completely understood. One of its most studied as-
pects is the cochlear amplification. In vivo experiments suggest that the cochlear amplifier is compressively non-
linear, has sharp tuning and prone to otoacoustic emissions. It is hypothesized in the literature that all of these
features can be modeled by the so-called Hopf oscillator. However, the Hopf normal form is a local model not
designed to be forced by a large variation of amplitudes and it has to be tuned near instability whose mechanism
remains to be uncovered. In this talk we present alternative models that reproduce the experimental observa-
tions equally well as the Hopf oscillator. In fact, one can build a phenomenological model without the need to be
tuned near a bifurcation. We also introduce two physiological models, one of them is an outer hair cell model pro-
posed by Ó Maoiléidigh and Jülicher that accounts for features such as hair bundle movement, adaptation and
charge movement inside the cell. We find that it is not necessary to tune this model into the region where Hopf
bifurcations occur to reproduce the characteristic nonlinearity. Our final model uses the essence of the outer hair

  

Source: Akhmedov, Azer - Department of Mathematics, University of California at Santa Barbara

 

Collections: Mathematics