There are three main parts to the ear: the outer, middle and inner ear. The outer ear is the part that you can see and includes the ear canal. The eardrum (tympanic membrane) separates the outer ear from the middle ear. There are three small bones, called ossicles, in the middle ear. The ossicles help transfer sound to the inner ear. The inner ear contains the hearing (auditory) nerve, which leads to the brain.
Normal_ear_anatomy

Any source of sound sends vibrations or sound waves into the air. These funnel through the ear opening, down the ear canal, and strike the eardrum, causing it to vibrate. The vibrations are passed to the small bones of the middle ear, which are then transmitted to the hearing nerve in the inner ear. Here, the vibrations become nerve impulses and go directly to the brain, which interprets the impulses as sound.