Perceptual auditory stream segregation of sequences of complex sounds in subjects with normal and impaired hearing

The influence of hearing loss and aging on the perceptual organization of s ound sequences was investigated by comparing the ability of young normal-he aring subjects and elderly subjects having either impaired or normal hearin g for their age to form perceptual auditory streams from sequences of harmo nic complex tones as a function of differences in fundamental frequency (F0 ). The sequences consisted of repeating triplets of harmonic complex tones separated by a silence (ABA-). In conditions in which the F0s of the A and B tone were so low that the harmonics could not be individually resolved by the peripheral auditory system even in the young normal-hearing subjects, those subjects showed similar stream segregation performance to the elderly hearing-imp aired subjects. In contrast, when the F0s of the tones were hi gh enough for the harmonics to be largely resolved at the auditory peripher y in normal-hearing subjects, but presumably unresolved in the elderly subj ects, the former showed significantly more stream segregation than the latt er. These results, which cannot be consistently explained in terms of age d ifferences, suggest that auditory stream segregation is adversely affected by reduced peripheral frequency selectivity of elderly individuals. This fi nding has implications for the understanding of the listening difficulties experienced by elderly individuals in cocktail-party situations.