The effects of age and interaural delay on detecting a change in interaural correlation: The role of temporal jitter.

Duration thresholds for detecting a change in interaural correlation (from 0 to 1, or from 1 to 0) in the initial portion of a 1-second, broadband noise (0-10 kHz) were determined for younger and older adults in a two-interval, two-alternative forced choice paradigm as a function of the interaural delay between the noise bursts presented to each ear. When the interaural delay was 0 ms, older adults found it harder to detect a change in correlation from 0 to 1 than from 1 to 0. For younger adults, however, this pattern was reversed. For interaural delays greater than 0 ms, both younger adults and older adults found it easier to detect a change in interaural correlation from 0 to 1 for short interaural delays (1 ms) with the reverse being true for longer interaural delays (5 ms). It is shown that this pattern of results is expected if temporal jitter (loss of neural synchrony in the auditory system) increases with age and with interaural delay. The implications of these results for age-related changes in stream segregation are discussed.