The role of temporal cues in voluntary stream segregation in cochlear implant listeners

Cochlear implant (CI) listeners experience difficulties in complex listening scenarios, where the auditory system is required to segregate a target signal from the competing sound sources. The present study investigated segregation abilities of CI listeners as a function of temporal cues and examined whether a two-stream percept occurs instantaneously or needs time to build up.

CI users participated in a detection task where a sequence of regularly presented bursts of pulses (“B”) on a single electrode interleaved with an irregular sequence (“A”) presented on the same electrode with a different pulse rate. The pulse rate difference and the duration of the sequences were varied between trials.

In half of the trials, a delay was added to the last burst of the regular A sequence and the listeners were asked to detect this delay. As the period between consecutive B bursts was jittered, time judgments between the A and B sequences did not provide a reliable cue to perform the task such that the segregation of A and B should improve performance.

The results showed that performance improved with increasing rate differences and increasing sequence duration, suggesting that CI listeners can segregate sounds based on temporal cues and that this percept builds up over time.