ANALYSIS OF THE MICROPIPET EXPERIMENT WITH THE ANISOTROPIC OUTER HAIRCELL-WALL

The in-plane and bending stiffnesses of the outer hair cell wall are c haracteristics crucial to the understanding of force and energy transm ission between cochlear elements. A mathematical interpretation is giv en of the micropipet experiment directed at determining the outer hair cell wall stiffness. On the basis of the microstructural observation of the wall showing that it comprises protein networks with different elastic properties, the model of an orthotropic cylindrical shell is u sed. The boundary-value problem is analyzed corresponding to the stres s-strain state of the wall (shell) caused by the action of the micropi pet. The solution is given in terms df Fourier series with respect to the circumferential coordinate. An asymptotic analysis of the solution is developed and an approximate formula for the length of the tongue aspirated within the pipet is derived. This leads to an analytical exp ression for the stiffness parameter measured in the micropipet experim ent in terms of Young's moduli and Poisson's ratios of the wall. This expression is an important part of the estimation of the elastic const ants of the wall. (C) 1998 Acoustical Society of America. [S0001-4966( 98)03602-9].