setUpVibratoOnPlay = function(that, arg, Wad){
	that.vibrato.wad = new Wad({
		source : that.vibrato.shape,
		pitch  : that.vibrato.speed,
		volume : that.vibrato.magnitude,
		env    : {
			attack : that.vibrato.attack
		},
		destination : that.soundSource.frequency
	});
	that.vibrato.wad.play();
}
Initialize and configure a vibrato LFO Wad for playback *