About the ear

The outer ear is formed by the area in front of the eardrum - the auricle and the outer ear canal. Sound waves arrive here and guided inwards through the auricle like a funnel.

The outer ear canal is shaped to: 

• amplify the oscillating air that arrives, like in a resonator
• improve our hearing by preventing wind and air movements from causing strong background noise.

The middle ear is the area behind the thin membrane of the eardrum. When the eardrum is hit by sound waves, tiny oscillations reach the three little ossicles: the hammer, anvil and stirrup – the smallest bones in the human body.
 

Thanks to their unique location, these tiny bones can amplify the oscillations 20-fold, guaranteeing sound reaches the inner ear.

From the middle ear, the eustachian tube extends to the nose and throat area. This tube ventilates the middle ear and equalises pressure.

The inner ear begins where the stirrup hits the next membrane – known as the oval window - which contains the organ of equilibrium and the cochlear.

 
The cochlear resembles a snail shell and is approximately the size of a pea. It contains three canals filled with a liquid.

 
The first canal directs the signals conducted into the liquid to the tip and back via a second canal. The central canal is home to the actual organ of hearing, the organ of Corti. The bottom is covered in thousands of tiny hairs.

 
The wave movements in the liquid-filled canals change depending on frequency. The hairs are only triggered by loud noises. The deeper the tones the further back in the cochlear the tiny hairs move, while high tones trigger the hair cells at the beginning of the cochlear.

 
Damage or “wear” of these tiny hairs in the cochlear is one of the main reasons for age related hearing loss.

Even when sound waves arrive in the inner ear they still have no meaning. Once conducted to the auditory nerve, the sound waves are converted to electrical signals that first hit the brain stem.
 

The signal is conducted to the areas of the brain responsible for emotional assessment. So, meaning is attached to tones connected to existing patterns in the cortex. This enables us to understand speech, recognise the voice of a friend and judge dangerous situations.
 

This means our hearing only works if the signal is sent perfectly from one station to the other and only once oscillating air has been turned into a warning signal, pleasant music or a coherent sentence.