Clinical Research Studies

Despite the impoverished information provided by a cochlear implant (CI), patients are unable to use all of the information provided by the CI speech processor. With a CI, pitch is presented by the location in the cochlea in which electric stimulation is presented. Typically, the cochlear location (and therefore the pitch) corresponds to the physical electrode locations. Unfortunately the electric fields provided by stimulation on a single electrode are broad and as a result, adjacent electrodes typically stimulate overlapping neural populations in the cochlea. Therefore, even with 12 to 22 electrodes in a modern implant, CI users typically perform as if they only have approximately 8 electrodes. A technique known as "current focusing" involves simultaneously stimulating on multiple electrodes out of phase, resulting in a reduction in electrical spread within the cochlea. Current focusing may reduce channel interaction and thereby increase the amount of independent information perceived from electrical stimulation. Depending on patient-related factors (e.g., neuronal health, location of electrodes, etc.), individual CI users may or may not benefit from current focusing. The overall goals of this research are to improve CI users' performance via current focusing and to identify CI users that may benefit from focused stimulation. We hypothesize that if current focusing can reduce the spread of excitation, then channel interaction will be reduced and the spectral resolution will be increased, thereby CI performance in challenging listening conditions (e.g., speech in noise, music perception). If current focusing is applied 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 efficient transmission of the maximum amount of spectral cues for each patient. In order to achieve the goals of the study, we will conducting a number of speech and hearing tests.