Temporal Regularity Detection and Rate Discrimination in Cochlear-Implant Listeners.

Area of Science:

• Auditory Neuroscience
• Biomedical Engineering
• Speech and Hearing Science

Background:

• Cochlear implants (CIs) primarily use temporal cues for fundamental frequency information.
• Temporal pitch perception in CI users is often weak, deteriorating significantly with increasing pulse rates (above 300 pulses-per-second).
• This weakness may stem from limitations in coding inter-pulse timing intervals via electrical stimulation.

Purpose of the Study:

• To investigate the relationship between temporal pitch perception and temporal regularity detection in cochlear implant users.
• To determine if impaired temporal coding underlies poor rate pitch perception.
• To compare performance on jitter detection and rate pitch discrimination tasks.

Main Methods:

• Direct electrical stimulation was used in cochlear implant recipients.
• Stimuli were presented at two pulse rates (100 and 300 pulses-per-second) on mid-array and apical electrodes.
• Listeners performed both a jitter detection task and a rate pitch discrimination task.

Main Results:

• Performance on both tasks worsened at the higher pulse rate (300 pps) compared to the lower rate (100 pps).
• Performance did not significantly differ between the mid-array and apical electrodes.
• A large inter- and intra-listener variability was observed, with no strong correlation between performance on the two tasks.

Conclusions:

• Rate pitch judgment and temporal regularity detection appear to involve distinct, task-specific neural processes.
• The findings suggest that limitations in coding temporal intervals contribute to weak temporal pitch perception in cochlear implant users.
• Individual differences play a significant role in the ability to utilize temporal cues for pitch perception.