Sound consists of vibrations of air in the form of waves. The ear is able to pick up these vibrations and convert them into electrical signals that are sent to the brain. In the brain, these signals are translated into meaningful information, such as language or music with qualities like volume and pitch. The volume of sound is measured in decibels (dB).

	The ear consists of three parts: the outer ear, middle ear and inner ear. The outer ear is the visible part of the ear on either side of the head and includes the ear canals that go into the head. The fleshy parts of the outer ear act as "collectors" of sound waves, which then travel down the ear canal to the eardrum. This is a membrane of tissue that separates the outer ear from the middle ear. The sound waves cause the eardrum to vibrate. This vibration is passed on to the middle ear, which consists of three small bones called the ossicles, which amplify and conduct the vibrations of the eardrum to the inner ear. The inner ear consists of an organ called the cochlea, which is shaped like a snail's shell. The cochlea contains tiny cells called hair cells, which move in response to the vibrations passed from the ossicles. Further amplification and modification occurs here. The movement of these hair cells generates an electrical signal that is transmitted to the brain through the auditory nerve.

© Fergusons Hearing Aid Clinic Limited 2006-. All rights reserved. Disclaimer