Auditory stream segregation with cochlear implants: A preliminary report

Auditory stream segregation was measured in cochlear implant (CI) listeners using a subjective "Yes-No" task in which listeners indicated whether a sequence of stimuli was perceived as two separate streams or not. Stimuli were brief, 50-ms pulse trains A and B, presented in an A_B_A_A_B_A... sequence, with 50 ms in between consecutive stimuli. All stimuli were carefully loudness-balanced prior to the experiments. The cochlear electrode location of A was fixed, while the location of B was varied systematically. Measures of electrode discrimination and subjective perceptual difference were also included for comparison. There was strong intersubject variation in the pattern of results. One of the participants participated in a second series of experiments, the results of which indicated that he was able to perceptually segregate stimuli that were different in cochlear electrode location, as well as stimuli that were different in temporal envelope. Although preliminary, these results suggest that it is possible for some cochlear implant listeners to perceptually segregate stimuli based on differences in cochlear location as well as temporal envelope.