About Hearing

The ear is a sophisticated organ that transmits the sounds we hear into electrical impulses that are interpreted by the brain. The process of hearing and interpreting sound is accomplished at a fantastic speed. To achieve this remarkable feat, each part of the ear - outer, middle and inner ear - fulfills a specific function.

Outer Ear
The outer ear is composed of the pinna, the familiar visible portion of the ear, and the ear canal. The shape of the outer ear serves to give preference to sounds originating from the front. The shape of the ear canal serves to enhance frequencies that are important for hearing speech.

Middle Ear
The middle ear consists of the eardrum, or tympanic membrane, and three tiny ear bones, or ossicles. The ossicles are the smallest bones in the human body. Although named the malleus, incus and stapes, they are often referred to as the hammer, anvil and stirrup because of their characteristic shape. Besides their role in the transmission of sound, these bones help to protect the ear from damage by constricting and limiting sound transmission when sound is too loud. The middle ear also contains the Eustachian tube, which connects with the throat, and serves to ventilate and regulate pressure in the middle ear.

Inner Ear
The inner ear is composed of the semi-circular canals, which are important for balance, and the fluid-filled, snail-shaped hearing organ, the cochlea.

How We Hear:

How the ear works normally:

1. Sound is transmitted as sound waves from the environment. The sound waves are gathered by the outer ear and sent down the ear canal to the eardrum.
2. The sound waves cause the eardrum to vibrate, which sets the three tiny bones in the middle ear into motion.
3. The motion of the bones causes the fluid in the inner ear or cochlea to move.
4. The movement of the inner ear fluid causes the hair cells in the cochlea to bend. The hair cells change the movement into electrical pulses.
5. These electrical impulses are transmitted to the hearing (auditory) nerve and up to the brain, where they are interpreted as sound.