PROJECT SUMMARY / ABSTRACT Cochlear implants (CIs) are the standard treatment for adults with moderate sloping to profound sensorineural hearing loss and enable sound awareness and spoken communication to a high majority of recipients. However, CI outcomes that rely on high-fidelity spectral encoding, such as music perception and speech understanding in noise, remain highly variable. One of the biggest contributors to this variability is channel interaction, but the relationship between spectral-dependent tasks (i.e., pitch, melody, timbre, and speech in noise perception) and channel interaction is not clearly defined. This study aims to manipulate channel interaction via spectral blurring in adult CI recipients to directly measure the effects of channel interaction on spectral-dependent tasks. We will also explore the use of image-based electrode selection as an approach for reducing channel interaction and its impact on music perception. Given that our preliminary data suggest a relationship between electrode placement and psychophysical pitch discrimination, we hypothesize that there will be a negative relationship between channel interaction and music perception outcomes. This hypothesis will be tested using a newly developed method of manipulating the excitation patterns of stimulation directly in CI recipients to investigate the causal relationship between channel interaction and outcomes. This model is advantageous over previous methods because it accounts for the effects of electrical stimulation, neural excitation, and sensorineural hearing loss present in actual CI-mediated listening. Primary Aim 1 will characterize the effects of channel interaction and the impact of spread of excitation (SOE) and electrode placement on pitch discrimination in all participants. Exploratory Aim 2 will measure the degree of image-based electrode selection benefit for CI-mediated pitch discrimination in a subset of participants. Collectively, these data will quantify channel interaction effects directly in CI recipients and provide a model to enable more detailed studies targeting potential uses of image-based electrode selection to improve CI-mediated listening. More broadly, this research should help improve signal processing methods for how stimuli, such as music and speech in noise, are encoded in CI stimulation, and lead to increased utilization of CIs by addressing CI recipient-driven concerns for variable outcomes. The training program will result in the development of knowledge and skills in: 1) auditory neurobiology and the consequences of sensorineural hearing loss, 2) CI signal processing and its limitations, 3) administering behavioral tasks of music perception to CI recipients, and 4) programming and administering direct stimulation experiments. It will also improve essential skills in grantspersonship, professional development, statistical analyses, and open science practices. Each of these skills is critical to achieving the applicant's goal of becoming a tenure-track faculty member at a research- intensive university with an independent line of NIH-funded CI outcomes research.

PROJECT NARRATIVE This study employs a novel approach to investigate the effects of channel interaction and a strategy that promotes channel independence to improve cochlear implant (CI) outcomes that require high-fidelity spectral encoding, such as music perception. Study results could provide the first evidence-based recommendations for programming CIs for music, which is of immediate interest to clinicians for counseling patients and programming devices, CI candidates for increasing utilization of CIs, and CI recipients for improving their performance and quality of life. More broadly, this study is of interest to CI researchers and manufacturers by providing a foundational model and preliminary data to inform future work striving to improve performance on other spectral tasks, such as speech understanding in background noise and musical sound quality and appraisal.