Tinnitus is basically a sound hallucination, and is very common among those suffering hearing loss or having been exposed to loud noise over an excessively long period of time.
I'm hard of hearing (with at least 70% hearing loss in both ears) since birth. Still, I get tinnitus very regularly, and it comes and goes. I live with it just as easily as I do with my hearing loss, but it can be a little hard trying to get back to sleep in the middle of the night when it's too loud, as I might might think the fire alarm went off or the phone was ringing!
There's not much you can do about it, unfortunately, but some people, like William Shatner, who played Capt. Kirk in Star Trek (he had to go through a lot of explosions as a part of the special effects in the series), have it so bad, they have to undergo a form of cognitive behavior therapy.