1. A method for optically and electrically stimulating neural tissue in the cochlea of a person, the cochlea having a length between a basal end of the cochlea and an apical end of the cochlea, in order to trigger compound nerve action potentials (CNAPs) that evoke auditory sensations for the person, the method comprising: delivering pulsed optical-stimulation signals to a plurality of different locations along the length of the cochlea from a first location near the basal end to second location that is closer to the apical end than is the first location; and delivering pulsed electrical-stimulation signals to one or more locations in the cochlea of the person that are closer to the apical end than is the second location.