Cochlear Implant Electrode Current Spread (2D)

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 2D simulator unrolls the coiled cochlear duct into a straight base-to-apex line with a 16-contact electrode array above it and an auditory-nerve fiber bundle below it, computing the same point-source electric-field model as the 3D version in real time and plotting it as a live potential profile. Switch between monopolar stimulation (one contact plus a distant ground, broad spread) and bipolar stimulation (current returns through the neighboring contact, sharply narrower spread on the return side), move which electrode fires along the array, adjust the injected current, and change how close the array sits to the modiolar wall — then drag to pan and scroll to zoom into any region of the duct while 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.