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In this series, Berkleemusic.com facilitator Loudon Stearns covers five ways tracks can interact with audio effects using Ableton Live.
The Fourth installment, Vocoder, shows how a Vocoder can be used to create an interaction between tracks. This example uses spoken word as the modulator, controlling a set of band pass filters, and an orchestral texture as the modulator, the signal running through the filters.
You can study with Loudon Stearns at Berkleemusic.com in the Advanced Production with Ableton Live, and Composing and Producing Electronic Music courses.