I've had on again, off again Tinnitus for years.
Way too much time spent down the front at raves sticking my head in the bass bins, followed up with a decade or more of attending a gig or two every week - not to mention 25 years of playing records has left my ears (especially my left) with a few issues.
As far as deafness goes they are in about as good a shape as a 45 year old man can be with that history (A little under average when tested 2 years ago) But when I'm tired the dreaded two-tone whistle kicks in.
When I was given this information on reddit a while back I couldn't believe that it worked.
It hasn't been a permanent fix for me, as after flying or gigs it can come back, but it does give some relief. The audiologist said I would just have to learn to live with it (and use the normal stuff of sleep and exercise)
I don't know anybody personally with a really chronic problem that has tried this, and people are getting varying results on the reddit thread, but there is no harming in trying it out for yourself.