The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea.

The name cochlea derives from Ancient Greek κοχλίας (kōhlias), meaning 'spiral, snail shell'.

More Info: en.wikipedia.org