The research objectives of this Program include the understanding of the ear and its functions in sound reception under normal and abnormal conditions in man and other animals. The principal methods of investigation include (1) the recording of electrophysiological activities of the ear during sound stimulation in terms of cochlear potentials and nerve action potentials, (2) determination of auditory acuity, discrimination, and frequency range by psychophysical and other means, including conditioned responses, electrodermal reactions, and general behavioral indications, and (3) correlation of the electrophysiological and behavioral data with anatomical and histological studies of the ear and its neural connections. A unifying concept in this relation is the evolution of the ear in vertebrates.