Like your other sense organs, your ears are extremely well-designed.
In fact, they serve two very important purposes. Do you know what they
are? You were probably able to figure out that your ears help you to hear
sounds, but what you probably did not know is that your ears also help
you to keep your balance.
How You Hear
When an object makes a noise, it sends vibrations (better known as
sound waves) speeding through the air. These vibrations are then funneled
into your ear canal by your outer ear. As the vibrations move into your
middle ear, they hit your eardrum and cause it to vibrate as well. This
sets off a chain reaction of vibrations. Your eardrum, which is smaller
and thinner than the nail on your pinky finger, vibrates the three smallest
bones in your body: first, the hammer, then the anvil, and finally, the
stirrup. The stirrup passes the vibrations into a coiled tube in the inner
ear called the cochlea.
The fluid-filled cochlea contains thousands of hair-like nerve endings
called cilia. When the stirrup causes the fluid in the cochlea to vibrate,
the cilia move. The cilia change the vibrations into messages that are
sent to the brain via the auditory nerve. The auditory nerve carries messages
from 25,000 receptors in your ear to your brain. Your brain then makes
sense of the messages and tells you what sounds you are hearing.
How You Keep Your Balance
Near the top of the cochlea are three loops called the semi-circular
canals. The canals are full of liquid also. When you move your head, the
liquid moves. It pushes against hairlike nerve endings, which send messages
to your brain. From these messages, your brain can tell whether or how
your body is moving.
If you have ever felt dizzy after having spun around on a carnival
ride, it was probably because the liquid inside the semicircular canals
swirled around inside your ears. This makes the hairs of the sensory cells
bend in all different directions, so the cells' signals confuse your brain.
What Did You Say?
Did you know that some people have trouble hearing and others cannot
hear at all? Well it's true. When a person can't hear well, a hearing aide
can sometimes help them hear better. However, people who are entirely deaf
have to rely on all their other senses to help process all of the information
from the world around them. They are deaf because of an illness or they
were born that way. You can also lose your ability to hear at an early
age by listening to things that are very loud. Scientists measure loudness
in decibels. Below is a table of various noises and their decibel level.
||Babies can get earaches because of milk backing up in the Eustachian
tube, which causes bacteria to grow and may cause hearing problems later
||When you go up to high elevations, the change in pressure causes your
ears to pop.
||Children have more sensitive ears than adults. They can recognize a
wider variety of noises.
||Dolphins have the best sense of hearing among animals. They are able
to hear 14 times better than humans.
||Animals hear more sounds than humans.
||An earache is caused by too much fluid putting pressure on your eardrum.
Earaches are often the result of an infection, allergies or a virus.