The inner ear
When the sound waves reach the inner ear, they enter the cochlea (8), which is a system of tubes shaped like the shell of a snail. The cochlea is filled with a watery liquid, which moves in response to the vibrations within the oval window. As the fluid moves, 25,000 tiny nerve endings are set in motion. They transform the movements into electrical impulses, which travel along the auditory nerve (9) to the brain. The brain then interprets these signals, and that is how we hear.