The cochlea is the sense organ that translates sound into nerve
impulses to the brain. Each person has two cochlea, one for each
ear. The cochlea is a fluid-filled, snail shaped cavern in the
boney part of your skull near each ear. Tiny bones in the middle
ear transmit sound from the ear drum across the middle ear and
vibrate against the cochlea. Vibrations in the fluid cause tiny
hair cells inside the cochlea to vibrate and generate nerve
impulses that then travel to the brain.