How much residual hearing is 'useful' for music perception with cochlear implants?

AIM

To compare performance on a song recognition task of bilaterally combined electric and acoustic hearing (bimodal stimulation) with electric or acoustic hearing alone.

METHODS

Subjects were 14 adults with cochlear implants (CI) who continued to use a hearing aid (HA) in one/both ears. Subjects were asked to identify excerpts from 15 popular songs, which were familiar to them, presented in a random order via a single loudspeaker. Presentation conditions were fixed in order: bimodal, CI alone and then HA alone. Musical excerpts were presented in each condition with and then without lyrics.

RESULTS

In a subgroup of subjects (n = 8) with better low-frequency residual hearing (thresholds <85 dB hearing level (HL)), mean scores for bimodal stimulation were significantly greater than for CI alone. In addition, mean 'no lyrics' scores for HA alone (59.7%) were significantly greater than for CI alone (38.8%). All of these subjects considered bimodal stimulation to be the most enjoyable way to listen to music. For the remaining subjects (n = 6) there was no benefit from using bimodal stimulation over CI alone, and the majority of these preferred to listen to music using CI alone.

CONCLUSIONS

Bimodal stimulation provides better perception of popular music, particularly melody recognition, compared to CI alone when low-frequency residual hearing is better than 85 dB HL.