Close your eyes REALLY hard and concentrate on the sound between your ears.
Do you hear a low rumbling sound, almost like thunder?
You can sometimes hear a similar sound when you yawn.
If you do, then you’re one of a special group of people who can hear that mysterious
sound between their ears—the sound caused by the tensor tympani muscle in the ear.
The human ear is comprised of three main sections—the outer (or external) ear, middle ear and inner ear
The auricle or pinna is the most visible part of the outer ear and is what most people refer
to when they use the word ‘ear’.
Sound waves first enter the outer ear and travel through the ear canal.
The ear canal channels the sound waves to the eardrum (or tympanic membrane)—a thin
but extremely sensitive membrane that is stretched tightly over the entrance to the middle ear.
The middle ear is the space that lies between the eardrum and the bony otic capsule of the inner ear
This section of the ear consists of two muscles, three tiny bones and numerous air spaces.
THIS is the part where all the action related to those low rumbling sounds occurs.
You see, just like the rest of the body, there are muscles in the ear as well, but unlike
the muscles present in your hands and legs, the muscles in the middle ear don’t move
anything that you can see.
There are two important muscles in the middle ear—the stapedius muscle and the tensor tympani muscle.
The low, rumbling sound that you hear when you shut your eyes really tight is caused
by the tensor tympani muscle.
The tensor tympani muscle originates from the Eustachian tube, which is also known as
the auditory tube.
From there, this muscle attaches to the malleus bone—one of the three tiny bones located
within the middle ear.
This malleus bone looks like a little hammer, and the tensor tympani muscle attaches to
the handle of this hammer.
When this muscle is contracted, or tensed, it pulls the malleus medially, tensing the
tympanic membrane and dampening vibrations in the ear ossicles, which results in reducing
the perceived amplitude of sounds.
In simple words, the tensor tympani muscle acts to dampen sounds within the ear.
Have you ever wondered why the sound of your own chewing is so low?
In fact, it’s so soft that we don’t really notice the sound of our chewing while eating
unless we’re trying to hear ourselves.
This happens because the tensor tympani muscle does a very good job at dampening the sound
produced by our own chewing.
Furthermore, the tympanic reflex helps prevent damage to the inner ear by dampening the transmission
of vibrations from the eardrum to the oval window.
In simple words, the tensor tympani muscle can actually block certain loud sounds that
fall on your ear FROM THE OUTSIDE and make them seem quieter to you.
For instance, when you hear a particularly loud sound, its waves can reach the insides
of your ear and do some real damage there.
The tensor tympani muscle in the middle ear plays a crucial role in preventing any harm
from occurring.
The moment a particularly loud sound falls on the muscle, it contracts or tenses up immediately,
which has a dampening effect on the incoming sound, thus making the sound seem quieter
to you.
However, the tympanic reflex has a response time of about 40 milliseconds, which isn’t
fast enough to shield the ear from sudden loud noises, like the sound of an explosion
or a gunshot.
That being said, it’s good for muffling the sound of loud thunder, which doesn't happen
in a split second, unlike an explosion.
The tensor tympani muscle is tensed involuntarily when we yawn, which produces a soft rumbling
sound.
Some people can contract the tensor tympani muscle voluntarily and can therefore hear
that low, rumbling sound in the ear for a few seconds before the sound dies off.
This happens because muscles vibrate when they tense up.
For instance, your hand shakes when you clench your fingers tightly to make a really firm
fist.
If you press a really tight fist against your ear, you can hear a low, wind-like sound emanating
from your hand!
So, next time you’re eating cereal, try to listen to the sound of your own chewing.
If it sounds impressively soft, remember that you have the tensor tympani muscle to thank!