www.tomatis.com
My son who is 4 is doing this, and after only a couple of weeks, he is able to go to the park and actually enjoy it. He is starting to make noises on purpose, like little babies do with rattles, just to hear what it feels like, which he never, ever did in his life. He talks in a louder voice, sings in public, and is pay more attention to his other senses, now that he is not so overwhelmed by sound.
It is so awesome- some of the things his listening therapist has taught us about:
bone conduction v.s. air conduction, his ability to hear noises at -10 decibles at certain frequencies, the different way his brain processes the sounds as they get louder and/or higher, his intolerance of noises above 20 decibles, how the vestibular system affects coordination, balance, and muscle tone, the list goes on and on.
He did a second test this week, and the range of processing problems has already decreased by something like 50%. Not sure what the long term affects will be, but right now we are all loving it.