WordNet sense 1 (an advocate who represents someone else's policy or purpose):

interpreter, representative, spokesperson

WordNet sense 2 (the sound made by the vibration of vocal folds modified by the resonance of the vocal tract):

vocalization, phonation, vocalisation, vox, vocalism

WordNet sense 3 (expressing in coherent verbal form):

articulation

WordNet sense 4 (the melody carried by a particular voice or instrument in polyphonic music):

part

WordNet sense 5 (utter with vibrating vocal chords):

sound, vocalize, vocalise