For people who cannot benefit from cochlear implants, there might be a chance with "Brain stem implants".  Some people get tumours on the auditory nerve, and removing these destroys the nerve.  If the tumours grow on both nerves, hearing loss is complete, and a cochlear implant is no use, because it relies on the auditory nerve to send messages to the brain stem.  The Germans in Freiburg are working on devices that stimulate the brain stem directly where the auditory nerve joins it.  This is still experimental, but maybe it will come soon.