THE EAR

The ear constantly picks up sounds, keeping us informed of what is happening around us. Sounds are caused by vibrations in the ear. The outer part of the ear is called the auricle or pinna. It traps sounds, and funnels them down the ear passage until they reach the eardrum. When the vibrations touch the drum, they make it vibrate. Three small bones behind the eardrum pick up the vibrations and pass them to another tight membrane, the oval window; thus they enter the inner ear and pass into the cochlea. Here, nerve endings pick up the vibrations and send them along the auditory nerve to the brain.

The brain changes the vibrations into sounds. In a street, you can hear a large variety of sounds; people walking and talking, traffic moving and workmen working. The brain can distinguish between different kinds of vibration, if they are loud enough. If the sounds are too loud, however, they can damage the eardrum.

·        Air pressure inside the ear is adjusted by the Eustachian tube to match the pressure on the outside. If the outside pressure changes too quickly, eg in an aeroplane, it will be painful – until your ears ‘pop’, equalizing the pressure.

·        The ears contain a kind of built-in spirit level, which helps you keep your balance, Nerve endings in the liquid in the semicircular canals of the inner ear pass information to the brain, which works out the position and movement of your head. Whizzing the body round and round upsets this, so that you feel dizzy.