Vocal pitch perception with cochlear implants

Abstract

Cochlear implant (CI) users often struggle to accurately perceive vocal pitch. This suggests that they are either not able to adequately use vocal pitch cues, such as temporal modulations resulting from F0, or they are using cues that do not correspond to vocal pitch. A potentially unreliable cue they may be using is formant spacing, which is correlated with vocal tract length. There is a gross, probabilistic relationship between vocal pitch and formant spacing since males tend to have both lower F0s and longer vocal tracts, but the relationship is weak, especially within gender. To examine if CI users are using the acoustic cues resulting from vocal tract length to make pitch judgments, CI users were presented with stimuli where the F0 was held constant but the formant spacing was systematically manipulated. Participants were presented with pairs of stimuli and asked to indicate the similarity of the pitch of the two stimuli using a seven-point Likert scale. The preliminary results indicate that CI users systematically perceived the changes in formant spacing as a change in pitch.