Perceived pitch of a sound depends on the location in the cochlea that the sound wave stimulated. High-frequency sound waves, which correspond to high-pitched noises, stimulate the basal region of the cochlea (red). Low-frequency sound waves are targeted to the apical region of the cochlear structure and correspond with low-pitched sounds (purple). Therefore, it is important for the cochlear implant electrode array to provide stimuli at multiple positions along the length of the cochlea.