The effect of the inter-target delay on informational and energetic masking of speech in younger and older adults

Abstract

In a reverberant environment where several people talk simultaneously, perceptual grouping of the direct wave emanating from a talker with its reflections is essential for both distinguishing different talkers and identifying attended speech. Older-adult listeners often feel it difficult to understand attended speech in reverberant environments. In this study, the effect of changing the time interval between target speech and its simulated reflection on recognition of target speech was investigated in both younger and older adults with normal or near normal hearing. When the masker was competing speech, the intelligibility of target speech was markedly improved in younger participants as the inter-target delay was reduced from 64 to 0 ms, particularly when the signal-to-masker ratio was sufficiently low (−6 or −8 dB). In older participants, the release induced by decreasing the inter-target delay was marked but smaller than that in younger participants especially at long inter-target delays (16 or 32 ms). Moreover, reduced release of target speech occurred if speech masker was replaced by noise masker. The results suggest that there is an age-related decline of the ability to perceptually integrate target speech with its reflections. This ability is particularly important for releasing speech from informational masking in reverberant environments.