1. A method for determining locations of an electrode array implanted in a cochlea of a living subject and spiral ganglion (SG) nerves that the electrode array stimulates, wherein the electrode array comprises a plurality of electrodes, comprising the steps of: (b) identifying an SG neural region that is targeted for stimulation and its corresponding modiolar interface; (c) constructing a tonotopic map of the modiolar interface to have a tonotopically mapped modiolar interface; and (d) identifying the position for each of the plurality of electrodes relative to the tonotopically mapped modiolar interface in vivo.