Defining the Relationship Between Channel Interaction and Outcomes in Adult Cochlear Implant Users

Purpose: Cochlear implant (CI) recipients demonstrate deficits in performance on spectral-dependent tasks, such as speech understanding in noise and music perception. Channel interaction, or the stimulation overlap between neighboring electrodes, contributes to poor spectral resolution with a CI. This study measured the impact of channel interaction on speech and music outcomes and investigated using an image-guided electrode selection strategy to reduce channel interaction and improve outcomes in a group of adult CI recipients. Methods: Channel interaction was measured using spectral blurring, a technique that artificially increases the stimulation overlap between neighboring electrodes to measure its effects on performance. Image-guided electrode selection was evaluated as a potential intervention for reducing channel interaction and improving outcomes. Dependent measures included tasks of auditory, speech, and music perception, as well as subjective ratings of sound quality and difficulty. Results: Findings provided direct evidence that channel interaction negatively impacts speech and pitch perception with a CI. For speech tasks, the results suggested that the specific frequencies involved in a particular task matter more than electrode placement factors. For music tasks, the results suggested that frequencies that rely primarily on place cues of pitch (>300 Hz) are more impacted by channel interaction than those frequencies that rely primarily on temporal cues of pitch (