Peripheral auditory processing in normal and abnormal ears: physiological considerations for attempts to compensate for auditory deficits by acoustic and electrical prostheses.

The processing of complex acoustic signals, such as speech, by the normal peripheral auditory system is described in terms of the properties of individual cochlear nerve fibres and the effects of lateral inhibition in the cochlear nucleus. The implications of the peripheral filtering of signals is indicated in psychophysical terms. In cochlear pathology, these filtering characteristics deteriorate, and the implications arising from the consequent deterioration in auditory frequency selectivity are outlined for the coding of loudness and for the analysis of speech. These considerations suggest theoretically ideal methods of compensation for recruitment by multichannel instantaneous compression, and for deterioration in format analysis by dichotic frequency partition. Finally, the implications for a minimal design for artificial electrical multi-electrode array stimulation of the cochlea in order to impart speech information to the profoundly deaf, are explored. Single wire stimulation, on the other hand, should be able to impart useful prosodic and minimal speech feature information to aid in lip reading and in the acquisition of speech.