Modal analysis of the diaphragm of the semicircular canal.

The aim of this paper is to determine the domain of validity of calculated quasi-static deformations of the cupula and of ciliar deflections on the crista ampullaris. Several three-dimensional models of the isolated ampullar diaphragm of the human semicircular canal and of that of the frog are studied theoretically by modal analysis. The four first modes of vibration are determined for each structure. Numerical simulations prove that for the first mode of vibration, the cupular deformation has the same shape as that obtained by applying a static pressure difference across the ampullar diaphragm. We studied also the effect of the mechanical properties (Young's modulus and Poisson's coefficient) of the components of the ampullar diaphragm on the vibration modes and their frequencies. The condition, which must be satisfied by the cupular internal viscosity, to have resonance near the natural frequency of the ampullar diaphragm is determined.