Cochlear-implant Listeners Listening to Cochlear-implant Simulated Speech

Channel vocoders with noise and sine-wave carriers are widely used to simulate modern multi-channel cochlear implants (CIs) in psychoacoustic experiments with normal hearing (NH) subjects. NH subjects perceive vocoded speech as impoverished and unnatural, but how CI listeners perceive vocoded sounds has not been systematically investigated. This letter reports that CI listeners could equally recognize both noise and sine-wave vocoded speech, albeit less well than NH listeners, and the recognition performance would not significantly increase beyond 8 channels. Nevertheless, they can easily discriminate up-to-80-channel vocoded speech from the original natural speech.