The objective is to apply the electron microscope to the histological study of the normal and pathological inner ear of the human in order to ellucidate the morphological basis of sensorineural hearing loss. Early postmortem material from individuals with normal hearing or known dysfunction of the inner ear will be obtained. Fixation is achieved in situ, and the temporal bone then is removed in the usual fashion at autopsy. The inner ear is then dissected, decalcified, and prepared for electron microscopy. Primary areas of interest would be the normal organ of Corti and the various forms of sensorineural hearing including presbycusis, ototoxicity, and genetic determined degeneration of the peripheral sense organ.