The Collaborative International Dictionary of English v.0.48:

Voice \Voice\, v. t. [imp. & p. p. Voiced; p. pr. & vb. n.
   Voicing.]
   1. To give utterance or expression to; to utter; to publish;
      to announce; to divulge; as, to voice the sentiments of
      the nation. "Rather assume thy right in silence and . . .
      then voice it with claims and challenges." --Bacon.
      [1913 Webster]

            It was voiced that the king purposed to put to death
            Edward Plantagenet.                   --Bacon.
      [1913 Webster]

   2. (Phon.) To utter with sonant or vocal tone; to pronounce
      with a narrowed glottis and rapid vibrations of the vocal
      cords; to speak above a whisper.
      [1913 Webster]

   3. To fit for producing the proper sounds; to regulate the
      tone of; as, to voice the pipes of an organ.
      [1913 Webster]

   4. To vote; to elect; to appoint. [Obs.] --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

voicing
    n 1: the act of adjusting an organ pipe (or wind instrument) so
         that it conforms to the standards of tone and pitch and
         color