Unfortunately, Cochlear has refused to properly space their electrodes, trying to jam 24 contacts (22 + 2 grounds) on the inch-long array into the pea-sized hearing organ. Because of this, channel crossover is a problem, where a given electrode stimulates the wrong part of the spiral ganglion, causing all sorts of problems.
For a description, see:
Cochlear Implant Channel Crossover: First Person Report at:
Then, to see how deafness f*cked with the wrong guy, check out how Mike Marzalek did it at:
Be sure to go to his biography page; and also do a patent search for his name.