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Your Ear: An Amazing Hearing and Balance System
The ear is an amazingly complex and sensitive organ of the body. Its
two primary functions are hearing and balance. Sound is collected and
amplified by the outer ear and middle ear. The inner ear converts sound
waves to signals or messages that are sent to the brain via the hearing
and balance nerve. In addition, the inner ear is responsible for maintaining
the body's orientation and sense of balance. Signals regarding your head
and body positions are transmitted to your brain via the hearing and balance
nerve, allowing you to maintain your balance.
Your ear is divided into three parts:
A -- Outer ear: the external, visible portion of the ear and the ear canal.
B -- Middle ear: the eardrum and three small bones (malleus, incus, and stapes).
C -- Inner ear: the cochlea (hearing canal), endolymphatic sac, semicircular
canals (balance canals), and the hearing and balance nerve.
How We Hear
Sound has to pass through all three parts of the ear in order for you
to hear.
- The outer ear and ear canal collect sound waves and guide them to
the eardrum, causing the eardrum to vibrate.
- The vibration of the eardrum vibrates the three tiny bones of the
middle ear, conducting the sound waves to the cochlea (hearing canal)
in the inner ear.
- The sound waves cause movement of fluid in the cochlea, stimulating
thousands of tiny, delicate hearing cells (hair cells) inside the cochlea
to sway back and forth.
- These hair cells are connected to tiny nerve fibers that join together
to make up the hearing nerve. As the tiny hair cells move, they initiate
electrical impulses that travel along the nerve fibers and auditory
nerve to the brain. The brain compares the electrical impulses it receives
to the sounds that it "knows", gives meaning to the sound, and we hear.

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