// How The Ear Works

Your ear is made up of three parts – these different parts are often referred to as the outer ear, the middle ear and the inner ear.

The Outer Ear

The outer ear starts with the bit that sticks out of the side of your head (called the pinna), continues through the ear hole and down a small tunnel called the ear canal until it reaches the eardrum.

The pinna acts like a funnel, catching sounds as they whizz past your head, enhancing them, and directing them down into your ear canal. At the end of the ear canal the sound hits the eardrum and vibrates it.

The Middle Ear

The other side of the ear drum (shown left) is attached to a tiny set of 3 bones called the hammer, the anvil and the stirrup (also known by their Latin names of malleus, incus, stapes) .

As the eardrum vibrates, the hammer, anvil and stirrup move backwards and forwards in time with the vibrations, causing the stirrup to vibrate something like a miniature eardrum called the oval window. It is estimated that this complete mechanism actually amplifies the sound about 22:1.

The Inner Ear

The inner ear has two parts:

The Cochlea:
The cochlea is a curled tube and acts as the hearing part of the inner ear. It contains an outer and inner chamber, both of which are filled with liquid. Within the inner chamber is the organ of corti, which contains thousands of hair cells, of which each one has minute formations called stereocilia. It also contains the auditory nerve, which sends signals to your brain.

The Semicircular Canals:
The semicircular canals are an element of your balance system, and are not used for hearing. As with the cochlea they are filled with liquid and contain hair cells. The semicircular canals work to send information to your brain about the direction your head is moving.

How you hear

When a sound is made it vibrates the air around it and creates what is known as sound waves. The outer ear gathers the sound waves, which then move along the ear canal and are transmitted to the eardrum. This in turn causes the eardrum to vibrate.

This vibration is then passed on to the ossicles, the three smallest bones in the body, which increase the sound and send it through to the inner ear. This causes the stereocilia within the cochlea to move, generating an electrical signal that is passed along the auditory nerve to the brain.

The brain is then able to interpret the signal and convert it into meaningful information such as language.