Tradeoff Between Spatial Resolution of Neural Excitation and Temporal Rate Processing

In this study, investigators will examine how temporal rate processing might be affected when the width of neural excitation narrows. The manipulation of neural excitation width will be achieved for example by changing electrode configurations or stimulating single versus multiple electrodes simultaneously. Investigators will then measure if the extent to which rate processing is affected by spatially restricted stimulation can predict a subject's overall speech recognition and predict also whether the subject is likely to benefit from a focused electrode configuration. Lastly, investigators will introduce and test a novel current focusing strategy where current focusing is applied in a channel specific manner and quantify if this intervention improves speech recognition. The primary endpoint of the study is speech recognition, and the secondary endpoint is psychophysical sensitivity to stimulation rate change.