The Vocoder features a voice-controlled synth mode – considered by many as the Holy Grail for vocoding.
Prior to VoiceTone Synth, vocoding required two audio signals: your voice (the exciter), and an instrument input (the carrier) to make cool vocoded sounds. Of course VoiceTone Synth supports the dual input method, but for artists who don't have another instrument or don't play one, VoiceTone Synth can generate a pitched synth part directly from your vocal and vocode that.
The result? Robot voices from one input: your voice.