I'm wondering the same about myself. I've had tinnitus for 1.5 years or so now, and it seems to have been (probably) caused by long term noise exposure (85 to 105dB or so, at least 5 days a week, for 5 or 6 years, 6 to 14 hours per day).
I'm looking forward to trying one of the new treatments that's currently being researched, either gene therapy or the drug therapy that's supposed to regrow the hair cells. But before I do, I want to know for sure whether the issue is the inner ear, the nerve, or just the brain being an idiot.
I had a hearing test with otoacoustic emission test, and so forth, and while it does show some very minor hearing loss, it is just that, and the emission test also showed some issues. I wonder if I should go back and have another test done as it's been almost a year. Kinda curious about it, I think I might.