FINITE-ELEMENT MODELING OF THE NORMAL AND SURGICALLY REPAIRED CAT MIDDLE-EAR

In this work, three-dimensional finite-element models of the normal an d surgically repaired cat middle ear were developed. The normal middle -ear model was formed by adding explicit representations for the footp late and cochlear load to an existing model of the cat eardrum. The fo otplate was modeled as a thin plate with a thickened rim. The cochlear load was represented by springs attached along the footplate's periph ery. The model is valid for frequencies below 1 kHz and for physiologi cal sound levels. Eardrum and manubrium displacements, and out-of-plan e displacements of the footplate's center, were found to compare well with experimental results. The normal model was modified to simulate t he effects of two types of middle-ear surgery, both of which are used to repair a discontinuous ossicular chain. Bulging of the footplate wa s found to occur when a prosthesis made direct contact with the footpl ate. The location of the prosthesis along the manubrium did not affect the motion of the footplate as long as the joints were all rigid. Whe n the joints were flexible, the largest displacements occurred when th e prosthesis was positioned near the upper end of the manubrium. (C) 1 996 Acoustical Society of America.