This is a laboratory study involving experiments to understand changes in modes of speech perception and language understanding as a function of aging. The experiments compare the performance of adults across the lifespan in speech perception faced with multiple sources of information. Young adults are compared with middle-aged adults and elderly persons in their identification of samples of speech composed of single or multiple sources of information. Their performance will be used to test how aging influences the relative value of each source of information about speech and the processing of each type of information. There are three lines of inquiry. The first involves the contribution of visible speech to speech perception. As acuity of hearing diminishes, individuals may compensate by paying close attention to configuration and movement of the lips. The second assesses the evaluation and integration of a variety of bottom-up sources of information in speech perception (audible and visible characteristics of speech). The third focuses on top-down sources such as phonological, lexical, semantic, and semantic constraints. Older adults have less information about some sources, but not about others. The experiments will determine to what extent elderly individuals have less information in communication and to what extent they process the information they have more or less efficiently than young adults. These measurements of how speech perception and language communication change with aging are necessary before it can be determined how any deficits might be compensated for in day-to-day communication.
