The theme of this section continues to be elucidation of the ways in which the information content of speech is affected by: 1) sensorineural hearing loss, and 2) various parameters of hearing-aid amplification. The ultimate goal is the development of amplification strategies that maximize the speech information available to hearing-impaired individuals. Work is proposed in four areas. In a collaborative project with Nelson, the frequency and temporal resolution abilities of subjects will be compared with their abilities to use frequency and temporal information in speech, as well as to recognize syllables and connected discourse. A second collaborative project (with Nelson, Speaks, and Viemeister) will define the effects of noise, both steady-state and fluctuating, on speech recognition by hearing-impaired persons. The goal of both projects is an advanced understanding of the extent to which speech recognition may be compromised by true deficits in auditory acuity, as opposed to stimulus conditions of low sensation level, high absolute level, and limited auditory bandwidth in which hearing-impaired persons usually must listen. If severe frequency resolution deficits do render spectral information in speech less usable for severely hearing-impaired persons, then the importance of temporal speech information may increase. A third project investigates importance of temporal information in conditions of reduced redundancy of spectral information, and determines the effects of amplitude compression in those conditions. A fourth project (with Speaks) will systematically define the predictive relationships between the intelligibility of connected discourse and other types of speech materials.
