Age-related differences in processing dynamic acoustic cues to initial stops.

Abstract

The present study examines possible age-related differences in the ability to process rapidly changing acoustic information in the identification and discrimination of initial stop consonants. As described in Fox etal. [J. Acoust. Soc. Am. 89, 1935(A) (1991)], older adults show lower accuracy rates in identifying both consonants and vowels in so-called ‘‘silent-center’’ tokens. Such results are compatible with the suggestion that older listeners have greater difficulty than younger listeners in processing dynamic acoustic cues, such as those represented by consonant transitions. Two sets of stimuli were created: one set represented a 7-step [beh]–[deh] continuum with a 40-ms transition followed by a 150-ms steady-state vowel; the second set was composed of a 7-step [beh]–[deh] continuum with the same transition followed by a 10-ms vowel. There were two sets of normal hearing listeners including 15 listeners aged 20–24 and 15 listeners aged 60–75. There was an identification task and two AX discrimination tasks (with either a 500- or 2000-ms ISI). Older listeners showed shallower slopes in their identification functions than did the younger listeners, particularly in the stimuli composed primarily of formant transitions. In the discrimination task, older listeners were significantly less sensitive to formant transition differences than were the younger listeners, but there were no significant differences related to interstimulus interval. [Work supported, in part, by an NIA grant to R. Fox.]