You know the low, muted rumble inside your ear that happens when you yawn? This sound is created by the tensor tympani muscle. Some people (myself included) can flex this muscle voluntarily, by itself, without any kind of yawn or tensing or opening of the jaw at all. If I do it lightly, it just makes a clicking sound. If I flex it with more force, it makes that low, muted rumble. I didn't know it was something that not everyone can do. Can you?