Long-term auditory adaptation to a modified peripheral frequency map.

Objective: Cochlear implants (CIs) attempt to mimic the tonotopicity of the normal ear by stimulating more basal regions of the cochlea in response to higher frequencies. However, there may be a mismatch between the normal place-frequency map and that implemented by a CI.

Material And Methods: Aiming to measure this potential mismatch and its changes over time, the present study used a method-of-adjustment procedure where CI users and normal-hearing listeners selected synthetic vowels to match prespecified vowel targets. Data from CI users were obtained longitudinally, starting on the day of initial stimulation and continuing for 2 years.

Results: CI users showed a significant amount of initial mismatch with respect to the normal-hearing listeners, but they also showed significant learning and adaptation over time and achieved nearly normal performance after some experience with the CI.

Conclusion: In general, the adaptation process took several months, suggesting that some CI users may benefit from alternative signal processing or rehabilitation procedures designed to facilitate perceptual learning after cochlear implantation.