Effects of lower frequency-to-electrode allocations on speech and pitch perception with the hybrid short-electrode cochlear implant.

Because some users of a Hybrid short-electrode cochlear implant (CI) lose their low-frequency residual hearing after receiving the CI, we tested whether increasing the CI speech processor frequency allocation range to include lower frequencies improves speech perception in these individuals. A secondary goal was to see if pitch perception changed after experience with the new CI frequency allocation. Three subjects who had lost all residual hearing in the implanted ear were recruited to use an experimental CI frequency allocation with a lower frequency cutoff than their current clinical frequency allocation. Speech and pitch perception results were collected at multiple time points throughout the study. In general, subjects showed little or no improvement for speech recognition with the experimental allocation when the CI was worn with a hearing aid in the contralateral ear. However, all 3 subjects showed changes in pitch perception that followed the changes in frequency allocations over time, consistent with previous studies showing that pitch perception changes upon provision of a CI.