I found this great article on Hack A Day about some research being done to enhance the quality of sound from Cochlear Implants with a method using light. Current solutions relay on electrical stimulus and only a small number of electrodes can be used at one time. This is because electrical signals are difficult to control and therefore stimulate more than just the target neuron. Micro light sources could enable researchers to dial in on smaller areas thus enhancing sound quality for the user.
Here is a simulation of what a Cochlear implant sounds like. Rebecca’s implants have 16 channels.