Ever notice when you chew the sound gets attenuated when you clamp down?
That's one of the automatic functions of the tensor tympani muscle. It also does it when you talk, and as part of your startle reflex. Fun fact: some people have conscious control of this muscle and can voluntarily "screw up their ears" (at least that's what it feels like, it also makes a roaring/rushing sound) to dampen sounds.
There's more tricks too, I'm able to close my nose by a muscle somewhere in the back of my throat. I've asked my friends if they could, but they al say they can't. Anyone else have that?