The cochlea is a fluid-filled, spiral-shaped cavity found in the inner ear that plays a vital role in the sense of hearing and participates in the process of auditory transduction. Sound waves are transduced into electrical impulses that the brain can interpret as individual sound frequencies. The spiral configuration of the cochlea allows for differing frequencies to stimulate specific areas along the spiral, which results in a tonotopic map that enables humans to perceive various frequencies of sound.

Source: National Library of Medicine