It has been observed that the response characteristics of the basilar membrane in
normal living cochleae are both frequency and level-sensitive (Robles & Ruggero
2001). The quality factor of the tuning curve is large at low sound levels and
decreases as the sound level increases, and the peak of the tuning curve moves
towards lower frequencies as the sound level increases. The current study proposes
a nonlinear cochlear model that responds adaptively to the incoming sounds via
feedback control arising from the mechanical attributes of the cochlear partition.
These attributes are dependent on the membrane potential of the outer hair cells
(He & Dallos 1999, Santos-Sacchi 1992). A parallel resistor-capacitor circuit analogy
of the outer hair cell with related perilymph and endolymph potentials is
designed to simulate sound-evoked changes in the outer hair cell membrane potential.
Nonlinear responses of the cochlea, such as compression and two tone
suppression, can be explained using this model. Furthermore, it has been shown
that the basilar membrane response to pure tone stimuli is attenuated by directly
stimulating the medial olivo-cochlear bundle using electrical shocks (Cooper &
Guinan 2006). Basilar membrane responses in the presence of efferent stimulation
can be demonstrated using the same model, through modulation of the outer hair
cell rnembrane potential. The proposed model provides a unified account of the
combined effect of sounds and efferent stimulation on cochlear responses.
Date of Award | 2010 |
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Original language | English |
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Awarding Institution | |
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A Biophysical Model of the Role of the Outer Hair Cell in Cochlear Nonlinearity
Jiang, B. (Author). 2010
Student thesis: PhD