Our ear helps us to hear and to keep our balance. Each ear has three parts: the outer ear, middle ear and inner ear.
The outer ear comprises the pinna (external ear flap) and auditory canal. The pinna collects sound waves and directs them through the external auditory canal towards the eardrum which is a thin 'skin' across the entrance of the middle ear.
The eardrum vibrates when it is hit by the sound waves. The sound vibrations are amplified at the same time and are transmitted to the tiny ear bones in the middle ear. These ear bones amplify the sound vibrations greatly and transmit them to the oval window of the inner ear.
The vibrations of the oval window cause the perilymph and endolymph of the cochlea to vibrate. When the endolymph vibrates, sensory nerve endings in the cochlea are stimulated and nerve impulses are generated. These impulses are relayed to the brain through the auditory nerve.
The auditory centre in the cerebral cortex of the brain interprets the nerve impulses as sounds.
When we are gaining height rapidly as we going up in a fast- moving lift or in a Peak tram, we may experience a short period of temporary deafness. This is because the eardrum can only vibrate properly when the pressure on its two sides is equal. As we are going up quickly, the atmospheric pressure decreases, but the pressure in the middle ear cannot adjust in pace. Therefore, the eardrum cannot vibrate properly, leading to a temporary deafness.
Normal hearing can be restored simply by blowing out air so that air leaves the middle ear to lower the pressure inside.