The Collaborative International Dictionary of English v.0.48:

Vox \Vox\, n. [L. See Voice.]
   A voice.
   [1913 Webster]

   Vox humana[L., human voice] (Mus.), a reed stop in an
      organ, made to imitate the human voice.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vox
    n 1: the sound made by the vibration of vocal folds modified by
         the resonance of the vocal tract; "a singer takes good care
         of his voice"; "the giraffe cannot make any vocalizations"
         [syn: voice, vocalization, vocalisation, vocalism,
         phonation, vox]