Effects of extreme tonotopic mismatches between bilateral cochlear implants on electric pitch perception: A case study

Objectives: Recent studies suggest that pitch perceived through cochlear implants (CIs) changes with experience to minimize spectral mismatches between electric and acoustic hearing. This study aimed to test whether perceived spectral mismatches are similarly minimized between two electric inputs. Design: Pitch perception was studied in a subject with a 10-mm CI in one ear and a 24-mm CI in the other ear. Both processors were programmed to allocate information from the same frequency range of 188-7938 Hz, despite the large differences in putative insertion depth and stimulated cochlear locations between the CIs. Results: After 2 and 3 years of experience, pitch-matched electrode pairs between CIs were aligned closer to the processor-provided frequencies than to cochlear position. Conclusions: Pitch perception may have adapted to reduce perceived spectral discrepancies between bilateral CI inputs, despite 2-3 octave differences in tonotopic mapping.