Cochlear implant (CI) users may be unable to access all of the spectral information provided by their devicebecause of channel interactions between electrodes. Current 'focusing' may reduce channel interaction andthereby improve spectral resolution. Depending on patient-related factors (e.g., neuronal health, location ofelectrodes, etc.), individual CI users may or may not benefit from current focusing. The overall goals of thisresearch are to improve CI users' functional spectral resolution via current focusing and to identify CI usersthat may benefit from focused stimulation. We hypothesize that if current focusing can reduce the spread ofexcitation, then channel interaction will be reduced and the spectral resolution will be increased, thereby CIperformance in challenging listening conditions (e.g., speech in noise, music perception). If current focusing isapplied to 'current steered' virtual channels, the spectral resolution may be further increased. Ultimately,current shaping (steering and focusing) can be optimized for individual CI users, allowing for efficienttransmission of the maximum amount of spectral cues for each patient.
In Specific Aim 1, we will measure the spread of excitation (SOE) for single electrodes at multiple cochlearlocations, with and without current focusing.
In Specific Aim 2, we will measure perception of simple multi-channel stimuli, with and without current focusing.
In Specific Aim 3, we will implement and evaluateexperimental signal processing strategies with and without current focusing.Taken together, these experiments will provide important insights regarding the relevance of the SOE forperception of complex multi-channel stimuli, as well as guidance toward optimizing current shaping forindividual CI patients in a clinical setting. The proposed research is significant because it aims to: a) improveCI performance in challenging listening conditions, b) develop current-shaping strategies for clinicalprocessors, and c) create quick clinical tests to optimize current shaping for individual patients. The research isinnovative in that it seeks to develop and implement new signal processing strategies to improve CI users'spectral resolution. The research approach combines objective measures (ECAPs), subjective descriptors,single- and multi-channel psychophysics, and evaluations of experimental signal processing to betterunderstand who might benefit from current focusing, and under what circumstances.
Cochlear implant (CI) users have difficulty in challenging listening conditions (e.g. speech in noise and musicperception) presumably because of channel interactions from each electrode. We will investigate if ''current-focusing'' will reduce the spread of excitation; increase spectral resolution; and provide better performance indifficult listening conditions. Furthermore; we will investigate quick (i.e. clinically-relevant) methods ofdetermining which patients would benefit from restricting the spread of excitation.
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