Voice pitch processing with cochlear implants

Cochlear implants today allow many severe-to-profoundly hearing-impaired individuals to hear and understand speech in everyday settings. However, the transmission of voice pitch information via the device is severely limited. Other than limiting their appreciation of music, the lack of pitch information means that cochlear implant patients have difficulty with speaker/gender recognition, intonation and emotion perception, all of which limit speech communication in everyday life. In electrical stimulation via cochlear implants, the fine spectral detail necessary for conveying the harmonic structure of F0, is not available. Although the spectral cues for pitch are lost, the temporal periodicity cue for pitch may still be available to the listener after speech processing. Our previously published results indicate that adult cochlear implant listeners are sensitive to this periodicity cue and are able to use it in a voice-pitch-based intonation identification task. Ongoing experiments also suggest that different mechanisms may play a role in processing the temporal pitch cue when multiple channels are concurrently stimulated, rather than when a single channel is stimulated. Initial experiments with primary-school-aged children who were implanted before the age of five, indicate no significant differences between them and their normally hearing peers in performance in the intonation identification task. This suggests that cochlear implants can benefit at least some children with severe-to-profound hearing loss in voice-pitch processing, and points to the potential role of neural plasticity in adaptation to cochlear implants.