Effects of several variables on temporal‐order identification in young and elderly listeners.

Abstract

Four measures of temporal‐order identification were completed by young (N=35, 18–31 years) and elderly (N=151, 60–88 years) listeners under various stimulus conditions. Experiments spaced over several months used forced‐choice constant‐stimuli methods to determine the smallest stimulus onset asynchrony (SOA) between brief (40 or 70 ms) vowels that enabled identification of the stimulus sequence. Vowels in four words (pit, pet, pot, put) served as stimuli. The four measures of temporal‐order identification were: (1) monaural two‐item sequences; (2) monaural four‐item sequences; (3) dichotic two‐item vowel‐identification sequences; and (4) dichotic two‐item ear‐identification sequences. All listeners identified the vowels in isolation with better than 90% accuracy. Results indicated that elderly listeners performed significantly poorer on monaural and dichotic temporal‐order identification tasks than young listeners, although a large overlap in group distributions was observed. For both groups, the two‐item dichotic task was significantly harder than two‐item monaural. Increasing the attentional demands of the monaural task by randomizing the stimulus ear did not explain this difference. Using shorter duration stimuli did not alter performance in the monaural task but did improve performance in the dichotic task. Significant learning occurred for elderly listeners but not enough to eliminate the age‐group differences. [Work supported, in part, by NIA.]