Knowledge of the pathologic basis of disease is central to the study of medicine, including disorders affecting the auditory and vestibular systems. Otology is unique in that the inner ear is inaccessible during life and so, conventional techniques of pathologic study such as biopsy and surgical excision are not feasible. Consequently, insight into the pathologic basis of ear disease can only be obtained by postmortem study of temporal bones and by developing credible animal models. An improved understanding of the pathology and pathogenesis of disorders affecting the auditory and vestibular systems should lead to more rational diagnosis and clinical management of these diseases. The procurement, processing and study of human temporal bones is a time-consuming and costly endeavor which lies outside the purview of clinical departments of pathology, and is therefore a research endeavor that is performed in temporal bone laboratories. This proposal was developed in keeping with the guidelines announced in RFA-DC-11-003 that is meant to establish the NIDCD Otopathology Research Collaboration Network. Our goals include the following: 1. Investigate pathology of hearing loss caused by cochleovestibular schwannoma. 2. Investigate radiologic-histologic correlations in otosclerosis, and the pathogenetic mechanism of sensorineural hearing loss when otosclerosis involves the cochlea. 3. Investigate dynamics of sensory and non-sensory cell turnover in the human inner ear. 4. Establish a program for the training of future temporal bone researchers. 5. Cooperate with the NIDCD Otopathology Research Collaboration Network. The proposed research is designed to provide new knowledge and insight into the pathology and pathophysiology of otosclerosis, acoustic tumors and cell turnover in the inner ear, which, in turn, should lead to better methods of diagnosis and therapy.