Aging and the perception of temporally interleaved words

The purpose of this study was to examine differences between older and younger listeners in the ability to sequentially attend to and ignore words.

Participants (n = 13 older adults and 13 younger adults) completed a temporally interleaved word recognition task. On each trial, 10 words were presented, and participants were instructed to repeat back every other word while ignoring the intervening words. Three variables were examined: (1) whether the word strings that were to be attended and to be ignored created syntactically correct sentences; (2) whether the to-be-attended and to-be-ignored words were presented from the same or from different spatial locations; and (3) whether the five target words in each trial (and the five distractor words in each trial) were spoken by a single talker or by five different talkers. In addition, digit-span forward and digit-span backward were measured and used as variables in correlation analyses.

As a group, the younger participants outperformed the older listeners, particularly when the to-be-attended and to-be-ignored words were presented from the same spatial location (versus when they were presented with spatial separation). Compared with the younger participants, older listeners also made more error responses that were to-be-ignored words, although the proportion of errors that were not responses involving masking words did not significantly differ between groups. Scores on the digit-span-forward test (but not digit-span-backward scores or the degree of hearing loss) were associated with older individuals' performance on this temporally interleaved speech-recognition task.

The overall pattern of results suggests that factors other than threshold elevation contribute to speech-understanding problems experienced by older listeners. However, although younger adults outperformed older listeners on this interleaved sentence task, older and younger adults benefited, to a similar extent, from spatial separation of the to-be-attended and to-be-ignored words, and from having a consistent target talker within a trial.