The ear is the key element of the hearing system: this organ has the complex task of receiving sounds and transforming them into impulses, which are then sent to and interpreted by the brain. Examining the ear in detail, we find three distinct parts.

Outer ear
This consists of the auricle, commonly called the ear, which helps us to understand where a sound is coming from, and then there is the auditory canal and finally the thin membrane of the eardrum. When sounds reach the membrane, they are translated into vibrations, which are then transmitted further inside the ear.

Middle ear
In just one square centimetre of space the middle ear contains the three smallest bones in the human body: the hammer, anvil and stirrup. The movements of these bones, caused by the eardrum, are amplified twenty times so that all the fine details of sounds are transmitted to the inner ear, from single sounds to those of a whole orchestra.

Inner ear
Inside a small structure called the cochlea we find 40,000 sensitive hairs or cilia (20,000 per ear) which are able to share the work of translating sounds: some work with loud sounds, others with quiet sounds. The cilia translate the vibrations into electrical impulses, which travel along the fibres of the auditory nerve to reach the brain, where they cause the sensation of hearing.