Central auditory system plasticity and aural rehabilitation of adults.

Until recently, researchers used behavioral measures of identification and discrimination of speech and nonspeech stimuli to assess the effects of auditory deprivation, enhancement, and training. Recent advances in our ability to measure electrical activity in the auditory system in response to sound have made it possible for us to study how changes in auditory input (because of hearing loss, auditory input modification, or training) affect the function of the central auditory system. This article reviews the evidence of changes in the auditory cortex in mature animals and in humans with acquired sensorineural hearing loss as well as changes associated with auditory training in persons with normal hearing. The results of studies that measure psychoacoustic and speech-recognition performance of persons with hearing loss, with and without hearing aids, are interpreted within the framework of our new knowledge about plasticity of the auditory system. Applications of electrophysiologic techniques to hearing aid research and clinical practice are highlighted.