Sensory and Cognitive Constraints in Comprehension of Spoken Language in Adult Aging

Abstract

Comprehension of rapid speech in complex environments is constrained by a number of factors. On the sensory side, the listener must deal with rapid, often poorly articulated speech, a challenge that is exacerbated in older adults with high-frequency hearing loss and reduced efficiency in temporal processing and frequency discrimination. These "bottom-up" declines can be ameliorated by "top-down" use of linguistic context for recognition of words as the speech unfolds in time and also for retrospective recognition of an indistinct word based on the context that follows it. A second major factor in speech comprehension is the use of prosody, to include pitch contour, stress, and temporal patterning, such as the lengthening of clause-final words to signal that a clause boundary has been reached. In all adults, and especially older adults, these operations are constrained by limitations in working memory or processing resources, a factor that shows bidirectional interaction with sensory challenge. We describe work from our and others' laboratories on speech comprehension and memory investigating each of these factors in young and older adults with good hearing and with mild to moderate hearing loss.