How Does The Brain Perceive
How does a human 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.
While you are sitting in the meadow, you might hear a calm breeze,some bees
buzzing around and maybe some birds chirping. The wind rustles through grass and
creates sound waves. Your ears collect these sound waves and causes your eardrum to
also vibrate. The eardrum the makes your hammer, anvil, and stirrup. The stirrups
vibrations move the liquid in your inner ear and the cilia translate those vibrations into
something the brain can understand. The brain processes the messages and realizes that
you are hearing a calm breeze. The same thing would happen if you heard a bee buzzing
around, except the different sound waves that it makes would cause the ear to process a
message that would tell the brain that it is hearing a bee. Likewise for the birds, unless of
course its a bird you have never heard before, but we will assume you have. Since we
have experienced these sensations before, its like the noise...
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