I've looked into tinnitus causes and cures, I have it myself, but I'm older than you are. There is often no identifiable cause, and it can occur spontaneously, unprovoked by any sonic event. It also occurs in various ways, sometimes as pure tones, sometimes as hissing. There is no reliable cure, but there are many remedies, some herbal (I haven't tried them). One of the more interesting and promising methods of tinnitus control is through a method of conditioning using custom shaped noise at controlled exposure times and levels. The basic idea is to identify the frequency of the tinnitus, then stimulate the patient with broad spectrum noise at all frequencies except that of the tinnitus. The result is a sort of "reconditioning" of the auditory cortex, and over a period of conditioning in this way, like 6 months to a year, there is a fairly high success rate in reduction or elimination of tinnitus effects. The papers available online are mostly targeted to health professionals, not available to the average guy. None of the old links I saved are still good, so google away, you'll find several patents, devices, and products. The procedure for conditioning requires a detailed study of your hearing and profiling your specific tinnitus. Conditioning devices are small, have their own headphones, timers, etc. And they're expensive. I would caution against anyone attempting the conditioning on their own using personal music players and audio software, though as you can plainly see, it's not really limited by the availability of hardware or software.
edit: footnote: Personally, I can reduce my tinnitus be being well rested and less stressed. If I don't sleep well for a few days, or have something that causes unusually high stress, my tinnitus flares up. I also think that staying hydrated seems to help, though that's hard to confirm.
