Speaker
Description
Cochlear implants (CIs) reliably restore speech perception in quiet, but are widely assumed to provide no access to musical harmony due to spectro-temporal interactions at the electrode-nerve interface. While temporal fine structure is crucial for pitch perception in normal-hearing (NH) listeners, its role in CI perception is unclear. We therefore investigated whether spectrally sparse coding of musical chords reveals latent harmonic sensitivity in post-lingually deaf CI users by reduced spectro-temporal blurring under different stimulation strategies.In Experiment 1, 6 CI and 6 NH listeners completed an oddball task with frequent standard triads and infrequent deviant triads. Standards were either physically identical major chords or major chords built on varying root F0s, the latter requiring judgments of voice relations (i.e., chord structure) rather than tracking individual voices. Deviants differed by one semitone in one or two voices. CI listeners were tested with envelope-only, fine-structure, or combined stimulation strategies; NH listeners were trained on vocoded versions transmitting only envelope cues. CI listeners performed above chance in all conditions, with no effect of stimulation strategy. NH listeners performed substantially worse than CI listeners on the vocoded stimuli, suggesting that CI but not NH listeners can effectively extract harmonic information from temporal-envelope cues.In Experiment 2, 10 CI and 10 NH listeners judged harmonically conclusive (with respect to Western harmonic rules) versus inconclusive chord sequences. NH listeners showed high sensitivity, whereas for CI listeners half performed above chance, and half showed no sensitivity.These findings reveal latent harmonic sensitivity in CI users and clarify the roles of temporal-envelope and fine-structure cues in harmony perception.