Source: D4K: “Hearing"
Visit the D4K companion Web site to learn more about Hearing: D4K: “Hearing"
This video segment from IdahoPTV's D4K begins with a demonstration of how a sound is made and then shows how a sound wave is transmitted to the brain through the parts of the ear. Discover why loud sounds can be permanently harmful to your ears and how the cochlea is involved in helping you maintain your balance. Learn how people communicate when their hearing is lost.
[JOAN CARTAN-HANSEN] When you make a sound you create energy in the form of sound waves. A loud sound has taller waves than a soft one. These waves eventually enter your ears. The sound waves travel down the ear canal.
The ear canal is about an inch long and at its end is a thin piece of skin called the ear drum. The ear drum is stretched tight just like the top of a drum. When the sound waves hit the ear drum it begins to vibrate. That vibration makes 3 tiny bones in your middle ear begin to move. These 3 little bones are known as the hammer, anvil and stirrup because that's what they kind of look like. These 3 little bones transmit or move the sound waves along to the inner ear. They also increase the force of sound waves.
The sound waves then moved into a snail shaped structure called the cochlea. Its semi-circular canals are filled with fluid and 17,000 tiny hair-like tissues. Sound waves move through the fluid and the hair bends. Somehow the movement of those hairs stimulates the 30,000 nerve fibers leading to the occolistic nerve. That nerve carries the signal to the brain and the brain figures out what the sound is.
You need two ears to figure out where a sound comes from. Your brain figures the difference between the two sound levels and calculates the direction of the sound.
It's important to protect your hearing from loud sounds. Muscles in the middle ear protect the ear by stiffening the ear drum or by moving the stirrup bone away from the inner ear. But sudden loud sounds can break the ear drum or cause other damage and continued loud sounds can damage the tiny hairs in cochlea.
Be sure to wear hearing protection if you're going to be around loud noises and turn the volume down on your head phones because once your hearing is damaged, it can't be made all better.
About 200,000 Americans are deaf. That means they can't hear anything. Another 3 million have severe hearing problems. Some use hearing aids to amplify or increase the strength of sound waves so they can hear better. Others have a cochlear implant. That's where a small microphone helps transmit sound to the inner ear.
Individuals who are deaf or hard of hearing sometimes use sign language to communicate. Others can read lips. Communicating, whether it's with your ears or your hands is essential to life.
Oh, and by the way - your ears do one other things. Remember the cochlea? Movement of the fluid inside the cochlea tells your brain about your body position. That way you can tell up from down even with your eyes closed and when you spin around the fluid in the cochlea spins too and that explains why you feel dizzy.
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