Aging and speech-on-speech masking.

OBJECTIVES: A common complaint of many older adults is difficulty communicating in situations where they must focus on one talker in the presence of other people speaking. In listening environments containing multiple talkers, age-related changes may be caused by increased sensitivity to energetic masking, increased susceptibility to informational masking (e.g., confusion between the target voice and masking voices), and/or cognitive deficits. The purpose of the present study was to tease out these contributions to the difficulties that older adults experience in speech-on-speech masking situations.

DESIGN: Groups of younger, normal-hearing individuals and older adults with varying degrees of hearing sensitivity (n = 12 per group) participated in a study of sentence recognition in the presence of four types of maskers: a two-talker masker consisting of voices of the same sex as the target voice, a two-talker masker of voices of the opposite sex as the target, a signal-envelope-modulated noise derived from the two-talker complex, and a speech-shaped steady noise. Subjects also completed a voice discrimination task to determine the extent to which they were able to incidentally learn to tell apart the target voice from the same-sex masking voices and to examine whether this ability influenced speech-on-speech masking.

RESULTS: Results showed that older adults had significantly poorer performance in the presence of all four types of maskers, with the largest absolute difference for the same-sex masking condition. When the data were analyzed in terms of relative group differences (i.e., adjusting for absolute performance) the greatest effect was found for the opposite-sex masker. Degree of hearing loss was significantly related to performance in several listening conditions. Some older subjects demonstrated a reduced ability to discriminate between the masking and target voices; performance on this task was not related to speech recognition ability.

CONCLUSIONS: The overall pattern of results suggests that although amount of informational masking does not seem to differ between older and younger listeners, older adults (particularly those with hearing loss) evidence a deficit in the ability to selectively attend to a target voice, even when the masking voices are from talkers of the opposite sex. Possible explanations for these findings include problems understanding speech in the presence of a masker with temporal and spectral fluctuations and/or age-related changes in cognitive function.