cochlea
    n 1: the snail-shaped tube (in the inner ear coiled around the
         modiolus) where sound vibrations are converted into nerve
         impulses by the organ of Corti

Cochlea \Coch"le*a\ (k[o^]k"l[-e]*[.a]), n. [L., a snail, or
   snail shell, Gr. kochli`as a snail, fr. ko`chlos a shellfish
   with a spiral shell.] (Anat.)
   An appendage of the labyrinth of the internal ear, which is
   elongated and coiled into a spiral in mammals. See Ear.
   [1913 Webster]