Cortical encoding of pitch contour changes in cochlear implant users: a mismatch negativity study.

A better understanding of melodic pitch perception in cochlear implants (CIs) may guide signal processing and/or rehabilitation techniques to improve music perception and appreciation in CI patients. In this study, the mismatch negativity (MMN) in response to infrequent changes in 5-tone pitch contours was obtained in CI users and normal-hearing (NH) listeners. Melodic contour identification (MCI) was also measured. Results showed that MCI performance was poorer in CI than in NH subjects; the MMNs were missing in all CI subjects for the 1-semitone contours. The MMNs with the 5-semitone contours were observed in a smaller proportion of CI than NH subjects. Results suggest that encoding of pitch contour changes in CI users appears to be degraded, most likely due to the limited pitch cues provided by the CI and deafness-related compromise of brain substrates.