Tinnitus is the hearing equilevant of phantom limb pain for amputees. There is no sensory impluse in a frequency range and so the brain makes up a sound. Regular heavy doses of niacin have helped friends of mine but it can make your skin feel like it is crawling until you (maybe) aclimate.
Recent research indicates that personalized music therapy where the music is digitally clipped in the frequency that you are damage can significantly reduce the tinnitus (Proceedings of the National Academy of Sciences 107:1207-1210 (January 19))
I have it also from too much power tool noise. I haven't shot without ear plugs in years.
