Cochlear implants.

All presently devised single channel devices generate a primitive sensation of hearing by the mechanism of 'periodicity pitch'. No 'place pitch' encoding is possible. Although some enhancement of communicative skills with lip reading results, unaided speech discrimination is not possible. Definite psychological advantages for the totally deaf have been observed with these simple devices. Multiple segments of auditory nerve must be stimulated in a manner which will simulate the complex patterns of neural activity necessary for speech discrimination. Electrode optimization and the pathophysiological consequences of electrical stimulation of the auditory nerve can best be determined in animals. The perceptual consequences of electrical stimulation of the auditory nerve, however, can best be determined in man. How much we will have to innovate the methods of aural rehabilitation will depend upon how well we can generate perceptual speech patterns by electrical excitation of the auditory nerve.