from the Office of Publications and Information Dissemination

SOUND AND THE EAR
Each part of the ear has a special role to play in the hearing process. It's a process that begins only when sound reaches the ear.

Sound is created when an object vibrates (moves back and forth), pushing the air around it. The sound of thunder on a stormy night or the song on a music box sets the air in motion until the air molecules (ma'-le-kyools) closest to you begin the journey through your ear and up to your brain.

Think of your favorite sound. Let's follow what happens when the sound moves through each of the parts of your ear until you "hear" it.

The pinna of the outer ear functions like a baseball catcher's mitt to "catch" the sound waves and direct them down through the ear canal to the eardrum. The eardrum vibrates with the rhythm of the air molecules (sound waves) pushing against it.

As the sound waves move the eardrum, the bridge of three ossicles vibrates back and forth. This vibration moves the oval window, carrying the rhythm of your favorite sound into the inner ear.

When the sound waves move the inner ear fluid, the basilar membrane and the hair cells float in rhythm like a boat on the water. Next the hair or cilia (sil'-ee-uh) on top of the cell bend. This bending sends patterns of electrical signals through the nerve fibers of the nerve of hearing. A loud sound moves the hair cells much more than a soft sound. High pitch sounds, such as whistles or the speech consonants /t/ or /s/, cause a movement of the membrane and hair cells in a different place than low pitch sounds like drums or vowels.

The inner ear fluid needs some room for its movement. The round window bumps in and out as the fluid moves.

The electrical signals travel from the hair cells to the nerve of hearing up to the brain. The brain makes sense of the electrical patterns sent across the nerves and you "hear" your favorite sound.

MORE THAN HEARING
The ear is not just for hearing. Some parts have other functions as well. Wax in your ear canal protects the other parts of the ear from dirt and bugs. But, too much wax in your ear canal can block sound from traveling further, cause you to hear less, and might require some attention from your doctor.

Have you noticed that your ears sometimes tickle or hurt when you have a cold? The Eustachian tube makes it possible for a cold to cause this discomfort. It's through this passageway that cold germs travel from your nose and throat to your ears. The Eustachian tube has another helpful function: it can clear your ears when you yawn or swallow.

FIND THE WORDS:
In the grid of letters below are names of parts of the ear and other related words. Circle the twelve words hidden in the puzzle.

by Jennifer Skalka

If you've ever had an ear infection, you may have noticed that you didn't hear as well. This change in hearing happens when the space in the middle ear fills with liquid. The liquid keeps the eardrum and ossicles from moving freely, and thus your hearing may change. After you take some medication, the liquid usually dries up, and your middle ear parts are again set in motion by sound.

Have you ever visited an amusement park and gone on a ride that spins you around fast? If you have, you probably know what it feels like to be dizzy. Maybe you even closed your eyes so that-you would feel less dizzy. Let's find out why.

Two other parts of your inner ear, the semicircular canals and the vestibule (ves'-ti-byool), have nothing to do with hearing. These two parts of the inner ear provide information to the brain about your balance and the position of your body in space.

As you turn your body and head, different hair cells in the vestibule and semicircular canals change direction. When this happens, electrical signals are sent through the nerve fibers which connect to your eye muscles. Your eyes move in different directions depending on how your body is twisting and turning. These signals send information to the brain that lets you know if you are standing on your head, doing a somersault, or simply jumping rope.

FILL IN THE BLANKS:
Choose the correct answers from the answer box below.

Copyright © 2003 Gallaudet University Laurent Clerc National Deaf Education Center
800 Florida Ave. NE
Washington, DC 20002
File 535/535-2--last revised 06/1998
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