Hello, this is Dr. David. I have read your question and am ready to help.these are not the only things possible. radiation therapy for nasopharyngeal cancer in the 1992 would have used lateral radiation fields which could easily have damaged or destroyed both cochea and so cochlear implants most likely will not be beneficial.
I am a radiation oncology doctor
there are more modern research into penetrating auditory-nerve electrodes which stimulate the auditory nerves directly in the brain which will work better for you than a cochlear implant. you will have to go to a large research university for a research techniques for this
these are called neural prosthetics for hearing
here is a website regarding the technology at Center for Neural Engineering and Prostheses (CNEP) at UC Berkeley and San Francisco