Learn how water is important when it comes to your inner ear, cochlea, and sense of hearing. Find out what cool names like the bony labyrinth, semicircular canals, ampulla, and vestibule mean.
Fluid in Your Ears
If you've ever been to a pool party, chances are it was really noisy. However, if you went into the pool and dove ever so slightly under the water, you would have noticed that the noise would have diminished considerably. With that in mind, you'd think that fluid would be something that hinders your ability to hear. The reality of the matter is that there is fluid in your ears that actually helps you hear better, not worse.
The fluid in our inner ears is what helps us to hear.
When sound reaches your ear, it vibrates your eardrum, which in turn vibrates little bones, called ossicles, in your middle ear. One of these ossicles, known as the stapes, will then vibrate a membrane called the oval window. This vibration is the key to understanding why fluid in your ears is critical to helping you hear the world around you.
The Inner Ear and Bony Labyrinth
The oval window is an opening covered by a membrane that separates the middle ear from the inner ear. Once the oval window begins to vibrate, it actually transmits sound waves that once traveled through the air into sound waves that will now travel through fluid. This transformation of sound waves traveling through air into sound waves traveling through fluid occurs in the inner ear. The inner ear is the innermost portion of the human ear and is involved in hearing and balance.
The Bony Labyrinth
The inner ear has a very strong outer wall made out of bone. We call this the bony labyrinth or osseous labyrinth. The bony labyrinth has three main parts:
- The cochlea
- The vestibule
- The semicircular canals
The cochlea is a fluid-filled structure in the inner ear responsible for converting the vibrations of sound waves into electrochemical impulses known as action potentials. As the ossicle called the stapes moves the oval window in and out, it causes the oval window to compress the fluid in the cochlea.
The three main parts of the bony labyrinth are the cochlea, vestibule and semicircular canals.
This action converts sound waves traveling in the air to waves traveling through fluid. Once these fluid waves begin to move around in the cochlea, they begin to stimulate little hairs inside of the cochlea.
This stimulation will eventually lead to the transmission of information stored as waves in the cochlear fluid into information that travels through electrical impulses. These electrical impulses will eventually reach the brain, where they will be interpreted into a sound.
The Vestibule and Semicircular Canals
While the cochlea is involved in hearing, the other two parts of the inner ear's bony labyrinth, the vestibule and semicircular canals, are involved in keeping you upright - your sense of balance, that is.
The vestibule detects changes in linear acceleration - that is to say, movement in one direction. For example, if you were to accelerate your car or ride down on an elevator, your vestibule would be responsible for the sensation of your body's movement in one plane or direction - either the horizontal or vertical plane.
However, if you were to start spinning your head around like crazy in a circle, the semicircular canals, which detect changes in angular acceleration - that is to say, rotational acceleration - would be most responsible for your sense of equilibrium in this particular case.
Each one of the three semicircular canals has a structure called an ampulla. The ampulla is a swelling at the end of each semicircular canal that contains an organ responsible for the sensation of angular acceleration and deceleration.
Let's go back to the beginning of this lesson to review what we have learned. The inner ear is the innermost portion of the human ear and is involved in hearing and balance. It is made of a strong, bony, outer wall called the bony labyrinth.
The bony labyrinth has three main parts: the vestibule, which detects changes in linear acceleration, the semicircular canals, which detect changes in angular acceleration, and the cochlea, which is a fluid-filled structure in the inner ear responsible for the conversion of vibrations of sound waves into electrochemical impulses.
Don't forget that you have six semicircular canals, three in each ear. Every semicircular canal has a structure called the ampulla, which is a swelling at the end of each semicircular canal, which contains an organ responsible for the sensation of angular acceleration and deceleration.
Upon finishing this lesson, you should be ready to:
- Decide whether fluid in the inner ear is helpful for hearing
- Discuss the structure and functions of the inner ear