Toward three-dimensional analysis of cochlear structure

est, however, are the propagation modes related to significant fluid displa cement and pressure in the different compartments of the organ of Corti, Re cent results from a three-dimensional model of the cochlea are summarized. The features include physically realistic values of basilar membrane stiffn ess, mass, and fluid viscosity. The simple 'feed-forward' principle for the active process yields results in qualitative agreement with recent mesurem ents in the cochlea. The limitation is a simplified representation of the o rgan of Corti, with two degrees of freedom representing the motion of the p ectinate and arcuate zones of the basilar membrane. However, the inner sulc us fluid flow is included. The new feature presented in this paper is an ap proach to treat all the structural detail of the organ of Corti, with the s ole input to the calculation in a form easily understood by anyone familiar with the cochlea. Specific results are shown for the Pakistani water buffa lo, since a fairly complete anatomical description of this cochlea is avail able. The static stiffness from the calculation, based on only the anatomy and known values for the protein elastic moduli, are in remarkable agreemen t with recent measurements in the gerbil cochlea. Only preliminary results for the dynamic response with inviscid fluid are reported. Of interest, how ever, are the propagation modes related to significant fluid displacement a nd pressure in the different compartments of the organ of Corti.