I can tell you how tinnitus works, as I've seen two presentations on it in Univeristy, and I can tell you my theory on how this technique remedies it.
It was described as follows.
On the exterior of your ear drum are tiny little hairs that ultimately go to your noggin nut in your head. There are many of them. And they work like a synthesizer or an organ does. With a synth or an organ, you press down a key, and it produces that note. You let off, and the note stops. Your drum hairs work the same way, and different frequencies of sound press down different hairs. Sound waves creating pressure inside your ear canal and on your drum pushes down these hairs, and sometimes these little hairs can get mashed down and stuck. This is like if your keyboard was ****ed up, you pressed a note and released, but the key stuck down and kept making the noise.
The human noggin nut deals with these stuck tones in two ways. It produces that tone constantly in your ear, or ignores it and kills the key. When it continues to produce that tone in your ear, you have our wonderfully obnoxious friend, tinnitus! When your noggin nut ignores the tone and kills the key, this is how you lose perception of certain frequencies over time.
Young children can hear high pitches that elderly people cannot hear. This is the noggin nut shutting the synth key off.
My theory on how this technique works is: when you produce the wonderful rumbly rumblies in your noggin, it stimulates and unsticks those keys. Probably through the pressure that goes through your brain soup to your ear drums when you give the ole taaaaapppy tap. Just taaaaaaaaapppy tap.