This is going to sound silly to most people, but I've been suffering from Tinnitus for a long time. This technique won't cure it but it certainly brings relief for me, to the point where I can ignore it.

When my Tinnitus is particularly piercing, I imagine it as a radiant bright white line in my head. I then mentally begin to reduce the radiance of the light until it is gone. This dulls the sound immensely, I'm still aware of it but it no longer hinders me.

For bonus points, I use a similar technique for getting rid of ear worms. In that case, I mentally put the song into a wooden box, close the lid and let it fall into the sea. Works every time.