The pinna collects sound waves travelling in the air and funnels them into the ear canal causing the ear drum to vibrate.
The eardrum is attached to three tiny bones (Ossicles) that are in turn attached to the Cochlea which move as a result of vibration of the eardrum.
The Cochlea (filled with fluid) moves as a result of vibration of the Ossicles. The movement of this fluid stimulate tiny rows of hair cells that respond to specific sound pitches. These movements in the hair cells are changed into nerve impulses, which are then sent to the brain along the auditory nerve.
Sounds are converted into electrical nerve impulses and sent along the CAP. This pathway is organised into various sections and together they work to carry sounds to the brain.