Effect of attentional demands and auditory memory degradation on vowel discrimination

Abstract

This study explores the effects of attentional demands in a vowel discrimination test when auditory memory has been degraded by irrelevant intervening nonspeech stimuli. The experiment utilized a same—different (AX) discrimination task with both within- and between-category pairs from an [i-I-ɛ] continuum. The interstimulus interval was 2000 ms in duration and was filled either with silence or 1, 2, or 3 short noise bursts. Listeners were required to make pairwise discriminations under two different attend conditions: (1) They either ignored any possible noise burst in the ISI and made only same/different judgments or (2) they made the same/different judgments and then indicated how many noise bursts occurred. Neither the noise condition nor the attend condition produced significant difference on the within-category discriminations. Increasing the number of noise bursts affected the listeners' ability to make between-category discriminations but there were no significant attend condition effects. Possible differences between younger and older adults will be addressed in terms of short-memory availability and/or attentional effects in speech discrimination. [Supported by Grant 1 R01 AG08353-01 from the National Institute on Aging.]