The purpose of this project is to describe the electrical field patterns generated within the cochlea by various intracochlear electrode array configurations. Field models of the cat and human cochleae will be constructed and evaluated using finite-element techniques. These models will be constructed in a progressive manner beginning first with investigations of the effects of fine anatomical structures [e.g. blood vessel through bone, anisotropic nerve bundle, perforated zone of the bony spiral lamina] on potential fields and current fluxes in simple ad hoc models. Once the appropriate level of anatomical detail required for accurate field models has been established, then histological sections of cat and human cochleae will be digitized to include the appropriate structures. Detailed analyses of current and potential fields will be conducted for clinically-applied and experimental electrodes, and the models' predictions will be validated by measurements of electrical fields in the cat cochlea. In addition, new electrode configurations that address the anatomical details of the human cochlea and the problem of variable neural survival will be evaluated in model studies.