This project will be the first large-scale investigation to evaluate changes in visual enhancement across the adult life span. Visual enhancement is the advantage afforded by seeing as well as hearing the talker, as compared to listening alone, and is an issue of critical significance to the audiological rehabilitation of older persons. The unique contributions of the present proposal are threefold. First, we will assess how vision-only speech recognition and auditory-visual integration skills contribute to changes in visual enhancement, and determine if changes relate to more global declines in older persons' abilities to integrate two sensory signals, be they speech or non-speech. Performance will be related to perceived communication handicap. Second, two quantitative models of auditory- visual integration, one developed by Blamey, Alcantara, Whitford, & Clark (1989) and the other by Braida (1991), will allow us to determine whether age affects how individuals integrate specific features of the speech signal, and also, how it affects their ability to achieve optimum integration of the auditory and visual signals. Third, we will determine whether or not the presence of hearing loss may affect integration performance for both older and younger adults, and whether the type of speech material interacts with one's ability to integrate. The results may affect several stages of the geriatric audiological rehabilitation plan, including how we assess speech recognition skills and the kinds of follow-up, support, and counseling we provide to clients and their families after an individual receives appropriate amplification. In addition, the results may have important theoretical implications for models of aging and auditory-visual speech recognition, and may elucidate variables that contribute to the communication handicap experienced by persons who have hearing loss. Over a five-year period 200 subjects, selected on the basis of age and hearing status, will be enrolled in a set of cross-sectional experiments. The experimental methodologies have been developed and tested through a series of extensive pilot studies. The experiments are designed to assess subjects' levels of visual enhancement, vision-only speech recognition, auditory-visual integration, auditory-auditory speech integration, and auditory-auditory non- speech integration. It is hypothesized that visual enhancement will be shown to decline with age, and that this decline will be associated with a global decline in the ability to integrate sensory information, not to a change in vision-only speech recognition abilities.
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