I can play a pure sine wave tone with a tone generator app, and dial the frequency up until it precisely matches my tinnitus. I originally did this just to determine that frequency.
But I noticed a side-effect: if I then turn off the tone generator, my tinnitus would disappear! Unfortunately that effect only lasts for a minute or less, so it is not really practical to get relief this way.
That is fascinating.
That's called "residual inhibition".
Note that I would be careful about using pure tones for too long. Pure tones end up focusing the energy in your cochlea towards a small area of hair cells. Since these cells don't regenerate, it may be wise to avoid overstressing them.