The Three Key Factors

 

Hearing is a complex process involving the coordination of many different parts of the ear and nervous system.  The travel of sound is broken down into three main parts.  The outer, middle, and inner ear.

 

The Outer Ear

Sounds from the outside world are picked up by the outer ear, which is made up of the pinna and the ear canal. As the sound waves enter the ear, the ear canal (1) serves to increase the loudness of those pitches that make it easier to understand speech. At the same time the ear canal protects another important part of the ear: the eardrum (2) - a flexible, circular membrane which vibrates when touched by sound waves.

 

The Middle Ear

The sound vibrations continue their journey into the middle ear, which contains three tiny bones called the ossicles (3-5), which are also known as the hammer, anvil and stirrup. These bones form the bridge from the eardrum into the inner ear. They increase and amplify the sound vibrations even more, before safely transmitting them on to the inner ear via the oval window.

 

The Inner Ear

The Inner Ear, or cochlea (8), resembles the circular shell of a snail, and houses a system of tubes which are filled with a watery fluid. As the sound waves pass through the oval window (6) the fluid begins to move, setting tiny hair cells in motion. In turn, these hairs transform the vibrations into electrical impulses that travel along the auditory nerve (9) to the brain itself. Exactly how the brain actually translates these nerve impulses remains a mystery.