Arthur Boothroyd
Graduate School, City Univ. of New York, 33 W. 42 St., New York, NY 10036
Speech perception requires the generation, by the perceiver, of language patterns believed to underlie the speech actions of a talker. At any moment, the perceiver's decisions are based on both direct sensory evidence and indirect contextual evidence. Depending on the perceiver's prior knowledge and perceptual skill, the value of contextual evidence can contribute 5 to 10 times as much information as sensory evidence in normal conversation. Impaired hearing reduces auditory sensory evidence by its effects on threshold, dynamic range, resolution, and susceptibility to noise, leading to increased dependence on visual and contextual evidence. Hearing aids and cochlear implants offer only partial solutions. Adult-acquired impairments, which affect only sensory evidence, are managed primarily by sensory assistance. Congenital and prelingually acquired impairments, however, also affect acquisition of knowledge and perceptual skill. As a result, sensory assistance, though necessary and important, is only the first step in a comprehensive program of management for hearing-impaired children. In this presentation, the foregoing outline will be supported with empirical data on the sensory capabilities of aided and implanted individuals and on the roles of vision and context in speech perception by the hearing impaired. [Work supported by NIH Grant No. 2PO1DC00178.]