The Sound of a Cochlear Implant Investigated in Patients With Single-Sided Deafness and a Cochlear Implant

HYPOTHESIS: A cochlear implant (CI) restores hearing in patients with profound sensorineural hearing loss by electrical stimulation of the auditory nerve. It is unknown how this electrical stimulation sounds.

BACKGROUND: Patients with single-sided deafness (SSD) and a CI form a unique population, since they can compare the sound of their CI with simulations of the CI sound played to their nonimplanted ear.

METHODS: We tested six stimuli (speech and music) in 10 SSD patients implanted with a CI (Cochlear Ltd). Patients listened to the original stimulus with their CI ear while their nonimplanted ear was masked. Subsequently, patients listened to two CI simulations, created with a vocoder, with their nonimplanted ear alone. They selected the CI simulation with greatest similarity to the sound as perceived by their CI ear and they graded similarity on a 1 to 10 scale. We tested three vocoders: two known from the literature, and one supplied by Cochlear Ltd. Two carriers (noise, sine) were tested for each vocoder.

RESULTS: Carrier noise and the vocoders from the literature were most often selected as best match to the sound as perceived by the CI ear. However, variability in selections was substantial both between patients and within patients between sound samples. The average grade for similarity was 6.8 for speech stimuli and 6.3 for music stimuli.

CONCLUSION: We obtained a fairly good impression of what a CI can sound like for SSD patients. This may help to better inform and educate patients and family members about the sound of a CI.