Delicate Sound of Thunder

For as long as I can remember, I've been able to make a rumbling sound in my ears.

All I have to do is think about it, and I hear a steady rumbling, like distant thunder. There's a very slight sensation of pressure that goes along with it. I can't keep it going indefinitely, but can make it last for about a minute.

I once described this to my mom and asked her to listen, ear-to-ear, to see if she could hear it too (she could not).

I've found only one use for this weird ability, to drown out loud noises. It's almost as effective as wearing ear plugs, except that I have to concentrate on it.

Today, on a fluke, I decided to 'Google' it, just to see if anyone else had the same thing. It turns out that I'm not crazy after all (or at least this is not one of the symptoms), a few people posted in various forums that they could produce this rumbling.

Then I found the answer: The Tensor Tympani is a muscle in the ear that puts pressure on the ear drum to reduce the amplitude of very loud noise (120 db and above), also it dampens the sound of chewing. At the very end of the Wikipedia entry I found my answer, which is elaborated in this footnote:

Individuals in a small percentage of the population can contract these muscles voluntarily even though the muscles normally contract only involuntarily. The voluntary contraction of these muscles vibrate not unlike the small vibrations in any muscle that is contracted very hard, say the muscles in your arm. You perceive these contracted middle ear muscle vibrations as a "rumbling noise" because the vibrations are transmitted (to) the middle ear bones and then to the inner ear. I suspect that you are among this small percentage of the population who can voluntarily contract the middle ear muscles.

All that, plus I can roll my tongue into a tube!