A DYNAMIC-MODEL OF OUTER HAIR CELL MOTILITY INCLUDING INTRACELLULAR AND EXTRACELLULAR FLUID VISCOSITY

The deformation response of a guinea pig outer hair cell is modeled fo r mechanical and electrical stimulation up to 25 kHz. The analysis use s a Fourier series technique for a finite length cell surrounded inter nally and externally by a much larger continuum of viscous fluid. The analytical solution predicts that outer hair cell length changes occur due to applied mechanical or electrical stimulation without significa nt resonance, characteristic of a highly damped system. The deformatio n is found to have little attenuation up to a corner frequency of abou t 2 kHz for long cells and 10 kHz for short cells, in agreement with p ublished experimental results. For electrical loading of 1 mV across t he lateral cell wall, deformation for short cells is calculated to be greater than 1 nm for frequencies up to 20 kHz. These results support the proposition that in vivo the outer hair cell modifies the characte r of basilar membrane deformation on a cycle-by-cycle basis. An estima te of the capability of the cell to supply energy to the basilar membr ane is given based on published values of outer hair cell material pro perties. (C) 1998 Acoustical Society of America.