Symmetry of Auditory Evoked Responses to Electric-Acoustic Pitch Matching in Unilaterally Implanted Cochlear Implant Patients

Background: We have recently established a possible objective physiological correlate of electric-acoustic pitch matching in unilaterally implanted cochlear implant (CI) participants with residual hearing in the non-implanted ear. However, these unilateral CI participants may have their CI implanted in either left ear or right ear.

Objective: To investigate the symmetry of auditory evoked responses to pitch matched/mismatched stimuli across two ears of normal hearing (NH) listeners and unilateral CI patients.

Methods:

Auditory Evoked Potentials (AEP) were obtained from 9 CI users (5 implanted in left ear and 4 implanted in right ear). For CI users, electrical and acoustic stimuli were presented in a continuously alternating fashion across ears. The acoustic stimulus were either matched or mismatched in pitch to the fixed electrical stimulus in the implanted ear. For NH participants, AEPs using acoustic tones presented to each ear that either matched or mismatched in frequency

Results: Our previous results with CI participants have shown there is shortening of N1 latency in the pitch matched condition. Our current results indicate that this pattern is observed whether the CI participants have CI in left or right ear, with relatively weaker effect in the right ear. NH listeners observed a similar pattern with a weaker effect.

Conclusion: Shortening of N1 in the pitch matched (CI) or frequency matched (NH) condition was present and this finding supports the potential utility of N1 latency as an index of pitch matching in cochlear implant users.