Revisiting Place-Pitch Match in CI Recipients Using 3D Imaging Analysis

Objective: To improve the estimation of the perceived pitch in a single-sided deaf cochlear implant (CI) listener by using accurate 3-dimensional (3D) image analysis of the cochlear electrode positions together with the predicted tonotopical function for humans. Methods: An SSD CI user underwent a Cone-Beam computed tomography (CBCT) scan. Electrode contacts were marked in 3D space in relation to the nearest point on the cochlear lateral wall. Distance to the base of the lateral wall was calculated and plotted against the place-pitch function for humans. An adaptive procedure was used to elicit the perceived pitch of electrically evoked stimulation by matching it with a contralateral acoustic pitch. Results: The electrically evoked pitch percept matched well with the calculated frequency. The median mismatch in octaves was 0.12 for our method in comparison to 0.69 using the conventional Stenvers view. Conclusion: A method of improved image analysis is described that can be used to predict the pitch percept on corresponding cochlear electrode positions. This method shows the potential of 3D imaging in CI fitting optimization.