How Does the Ear Work?

In general, the ear consists of three major sections: the outer, middle and inner ear. Sound is collected by the outer ear and funneled down the ear canal (outer ear). The sound vibrations cause movement of the eardrum and the chain of three tiny bones connected to it (middle ear). The middle ear system serves to intensify the energy of the sound vibrations and delivers them to the cochlea (inner ear). Inside the cochlea are thousands of tiny hair-like cells that connect to fibers of the hearing (acoustic) nerve. Sound vibrations entering the cochlea cause a wave to travel through the fluid-filled organ of hearing. This wave causes movement of the hair cells which then generate electro-chemical signals which travel through the acoustic nerve to the brain where they are recognized as sounds.

• The Outer Ear
• The Middle Ear
• The Inner Ear
• Types of Hearing Loss & Where They Occur

The Outer Ear

1) Outer ear (pinna). This is the part of the ear that we can see. The pinna acts as a sound collector and helps channel sound down the ear canal.

2) Ear canal. Ear wax (cerumen) is produced in the ear canal. The wax serves as a protective mechanism and helps to keep the ear canal clean.

3) Eardrum (tympanic membrane). The ear drum is so-named because it functions much like the head of a drum, vibrating when sound waves strike it.

The Middle Ear

The middle ear consists largely of empty space. 4--6 Ossicular Chain. This chain of 3 bones contains the smallest bones in the body. The Malleus (4) is attached to the eardrum. The middle bone is called the Incus (5) and the last bone is called the Stapes (6). The Stapes is connected to the oval window--a membrane leading into the cochlea. Sound vibrations striking the eardrum are made more intense by the piston-like action of the ossicular chain.

7) Eustachain tube. This tube leads from the middle ear space to the back of the throat and serves to equalize the air pressure on both sides of the eardrum. Unequal pressure is responsible for the "plugged" feeling you sometimes get when driving into the mountains or riding in an airplane. When the eustachian tube opens you feel a "pop" as the pressure is equalized and your ear feels "normal" again.

The Inner Ear

8) Balance (vestibular) canals. The vestibular system in your ear is part of the balance system for your body. The system contains sensory cells that provide information about the position and motion of your head.

9) Cochlea. The cochlea is shaped like the shell of a snail and contains the sensory organ of hearing. It is encased in the temporal bone, the hardest bone in the skull. The anatomy of the cochlea is very complex and the function of this marvelous organ is still not completely understood. The cochlea is coiled into approximately 2.5 turns and contains 3 fluid-filled compartments separated by Reisner's membrane and the basilar membrane.

Types of Hearing Loss & Where They Occur