LEAD

Richard Penninger
Professor German Hearing Center of the Hannover Medical School

Polyphonic Pitch Perception for Cochlear Implant Users

"They gave me back speech but not music" is a sentence commonly heard by CI subjects. One of the reasons is that in music, multiple streams are frequently played at the same time, which is an essential feature of harmony. Current CI speech processors do not allow CI users to perceive such complex polyphonic sounds.
Two recent studies will be described in which the ability of CI users to identify the number of simultaneous tones was assessed. First seven CI subjects were asked to identify the number of one single or two simultaneous tones. Stimuli were applied with a research sound processor thought direct electrical stimulation. Additionally, ten further CI subjects were asked to identify one, two and three simultaneous pitches applied on different electrodes using sinusoidal amplitude modulation. All stimuli were loudness balanced before the actual identification task.
When tones are presented optimally through a research sound processor, then CI users are able to perceive polyphonic tones. If sound processing strategies were to use concurrent stimulation on multiple or single electrodes, then possibly polyphonic tones would be better perceived by CI users yielding better music and language perception.