Cochlear Implant Electrode Current Spread

A cochlear implant's electrode array delivers current into the fluid-filled scala tympani, and that current does not stay confined to a single point — it spreads through the perilymph and recruits a whole neighborhood of auditory-nerve fibers along the modiolus. This simulator renders a 3D model of the human cochlear spiral with a 16-contact electrode array and an auditory-nerve fiber bundle, computing the electric potential from a point-source current model in real time. Switch between monopolar stimulation (one contact plus a distant ground, broad spread) and bipolar stimulation (current returns through the neighboring contact, sharply narrower spread), move which electrode fires along the base-to-apex array, adjust the injected current, and change how close the array sits to the modiolar wall — then watch the live fiber-recruitment count and spread-width readout show exactly how these choices trade off spatial selectivity against loudness, the physical root of why implant listeners resolve fewer independent pitch channels than they have physical electrodes.