Each ear is divided into three sections €“ the outer ear, the middle ear and the inner ear.

The outer ear consists of the pinna (the part outside the head) and the ear canal (a passage about 2.5cm in length along which sound travels). At the end of the ear canal is the paper-thin eardrum.

The middle ear is a space about 1.3cm across, filled with air. This space is connected to the back of the throat by the Eustachian tube. This tube is closed most of the time, but when we yawn, swallow or blow our noses, it opens. There may be a clicking sound in the ear when this happens €“ this is normal. It often happens during take off and landing in an aircraft and is simply a result of the body ensuring that air pressure inside the ear is the same as it is outside.

A chain of three tiny bones stretches right across the middle ear, passing sound from the eardrum to the inner ear, which has two parts €“ the cochlea (used for hearing) and the vestibular part (used for balance).