A quick guide to how hearing works

The ear is quite a piece of engineering. A complex organisation of bones, hairs, nerves and cells, it picks up sound waves, processes them and sends them to your brain. This all happens in real time, meaning the system operates almost instantaneously.

How hearing works

Sound travels in invisible waves through the air. It occurs when a moving or vibrating object causes the air around it to move, creating pressure waves (or sound waves) that radiate outwards from the source.

When these sound waves reach the ear, they travel down the ear canal and hit the eardrum, making it vibrate. Three tiny bones in the middle ear link the vibrating eardrum to a tiny bone structure in the inner ear called the cochlea.

The cochlea is filled with liquid that carries the vibrations to thousands of tiny hair cells. The movement in the fluid causes the cells to carry a message to the nerve that is connected to the brain, which turns the signals into what you hear.

Parts of your ear


The outer ear is made up of skin and cartilage on the outside, and the ear canal that leads down to the eardrum.

The middle ear begins at the eardrum, about 2.5 centimetres inside the head, and includes the little bones that carry the sound vibration to the area where hearing really begins.

The inner ear is where these vibrations are changed into the signal that is carried to the brain, which you experience as sound. This part of the ear also controls balance.

What causes hearing loss?

Hearing loss is usually caused by problems in the hearing pathway. The problem can be in the outer, middle or inner ear, or in the complex auditory nerve pathway to the brain.

Hearing loss can be present at or soon after birth. This is called congenital hearing loss. Or it can develop later, which is known as acquired hearing loss.

There are different types of hearing loss including conductive, sensorineural and a combination of both.

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