Acoustic streaming in the cochlea

This presentation examines the fluid motion resulting from airborne and bone conduction excitation in the cochlea. The time-averaged velocity, termed acoustic streaming, driven by the gradient of the Reynolds stress, is of particular interest. The effect of asymmetry in the oval and the round window velocity and its influence pressure gradient across the cochlear partition and acoustic streaming is explored. It is shown that the streaming flow is a function of the reciprocal of the Strouhal, 1/S and the oscillatory Reynolds number, 1/R, have a magnitude much less than one for frequencies of interest. The work presented will focus on the parameter range R/S2 = O(1). The streaming velocity is obtained in terms of asymptotic expansion in terms of the reciprocal of the Strouhal number. Solution of the streaming flow outside the viscous region is obtained using boundary conditions derived from a matched asymptotic analysis.