Some people can hear a rumbling sound just by tensing a muscle of ears
Even though most of the muscles in our skeletons are under our control, there is at least one we don’t always have a handle on. The tensor tympani is in the middle ear, and most people don’t seem to be able to contract it on their own.
People who can contract their tensor tympani, a small muscle above the auditory tube, have a special skill: when they do this, they hear a low rumbling sound that sounds like thunder.
This is not something new. On page 1,263 of Johannes Müller’s 1842 book Elements of Physiology Volume 2, he talks about how this muscle can be used to make sound by contracting on its own.
But a lot of the time, something that seems normal to you is strange to someone else, and vice versa. After all, the word “human” covers a wide range of different types of people.
Massimo, an Italian engineer who runs a science Twitter account, sent out a tweet that has again divided the internet into those who have and those who don’t, most of whom didn’t even know the other side existed before.
The tensor tympani has some important jobs to do when it comes to our hearing. Your eardrum moves when you hear something. This sound is sent to the malleus, incus, and stapes, which are bones that send sound waves to the inner ear.
The malleus is the part of the ear that is closest to the eardrum. It sends vibrations from the membrane to the incus. And the tensor tympani is linked to the malleus. When it contracts, it pulls the malleus away from the eardrum, which tightens the membrane of the eardrum (called the tympanic membrane, which is also the name of the muscle), making it less able to move and reducing the vibrations that reach the inner ear.
Tensor tympani does this automatically when there is a loud noise. This is thought to protect the inner ear cells from damage.
But the muscle is also thought to play two other roles. It can cover up low-frequency sounds, so we can hear high-frequency sounds better. It also gets a little smaller when we make sounds, like when we chew, cough, talk, or yawn. This is probably to keep us from being deafened by our own bodies.
When the tensor timpani contracts, all you hear is the sound of your own muscle. If you can control how much it contracts, it’s like putting your hands over your ears without your hands.
If you don’t know what’s going on, it can also be scary. A 2013 case report talks about a 27-year-old man who went to his doctor “complaining of voluntarily evoked bilateral tinnitus.” He was able to voluntarily contract both tensor tympani muscles, and the roaring noise wasn’t anything to worry about.
There is a way for those of us who can’t make our ears rumble on demand to hear what it sounds like. Have a big old yawn. Hear something rumbling and rushing? Your tensor tympani muscles are getting tighter. Pretty cool, right?
