Spiral tube of the inner ear that converts sound vibrations into nerve impulses (7)
I believe the answer is:
cochlea
(Other definitions for cochlea that I've seen before include "Part of the inner ear" , "A cloche (anag) - spiral cavity of the inner ear" , "there's a cavity, as we hear" , "Snail-shaped tube in the inner ear" , "Spiral tube in inner ear" .)