The ear is a complicated structure. It is usually divided into three different areas. The outer ear, the middle and inner ear. The outer ear is the shell-shaped part which you can easily see on the outside, combined with the canal. These channel the sound towards the eardrum.
The eardrum is the boundary between the outer and the middle ear. It catches the vibrations from the sound and transmits it to the ossicles in the middle ear. These are tiny bones which act as levers to amplify the sound, passing it towards the inner ear. The part of the inner ear concerned with hearing is called the cochlea. It converts the vibrations in the ossicles into nerve signals which are sent along a nerve to the brain.
The brain interprets the nerve signals as the sounds which we know so well. The system is very delicate. Loud noises contain a large amount of energy and can damage the system. It is important to wear a good pair of earplugs if you are going to be exposed to a loud noise. To start with the damage can be temporary, with mild deafness and tinnitus. After repeated or severe episodes the damage may be permanent.