The Effect of Aging and Priming on Same/Different Judgments Between Text and Partially Masked Speech

It is well known from previous research that when listeners are told what they are about to hear before a degraded or partially masked auditory signal is presented, the speech signal "pops out" of the background and becomes considerably more intelligible. The goal of this research was to explore whether this priming effect is as strong in older adults as in younger adults.

Fifty-six adults-28 older and 28 younger-listened to "nonsense" sentences spoken by a female talker in the presence of a 2-talker speech masker (also female) or a fluctuating speech-like noise masker at 5 signal-to-noise ratios. Just before, or just after, the auditory signal was presented, a typed caption was displayed on a computer screen. The caption sentence was either identical to the auditory sentence or differed by one key word. The subjects' task was to decide whether the caption and auditory messages were the same or different. Discrimination performance was reported in d'. The strength of the pop-out perception was inferred from the improvement in performance that was expected from the caption-before order of presentation. A subset of 12 subjects from each group made confidence judgments as they gave their responses, and also completed several cognitive tests.

Data showed a clear order effect for both subject groups and both maskers, with better same-different discrimination performance for the caption-before condition than the caption-after condition. However, for the two-talker masker, the younger adults obtained a larger and more consistent benefit from the caption-before order than the older adults across signal-to-noise ratios. Especially at the poorer signal-to-noise ratios, older subjects showed little evidence that they experienced the pop-out effect that is presumed to make the discrimination task easier. On average, older subjects also appeared to approach the task differently, being more reluctant than younger subjects to report that the captions and auditory sentences were the same. Correlation analyses indicated a significant negative association between age and priming benefit in the two-talker masker and nonsignificant associations between priming benefit in this masker and either high-frequency hearing loss or performance on the cognitive tasks.

Previous studies have shown that older adults are at least as good, if not better, at exploiting context in speech recognition, as compared with younger adults. The current results are not in disagreement with those findings but suggest that, under some conditions, the automatic priming process that may contribute to benefits from context is not as strong in older as in younger adults.