Reason: Using the Vocoder

A vocoder is an audio effect that lets you impose the dynamics and changing spectral content of one sound (the modulator) onto another (the carrier). The modulator is usually the human voice, speaking or singing, while the carrier is usually a bright synthesizer. (You can substitute drums for the voice and white noise for the synthesizer for some unusual effects.)

A notable example of a vocoder applied to a singing voice is Hide and Seek by Imogen Heap.

The vocoder works by analyzing the spectrum of the modulator using a bank of bandpass filters. The time-varying power of the signal emerging from these filters is used to control a bank of bandpass filters applied to the carrier signal. You can think of this process as the modulator filter levels automating the sliders of a graphic equalizer affecting the carrier.

Here is how to set up a vocoder in Reason to create the typical “talking synthesizer” effect.

  1. Create a SubTractor, and choose the Polysynth > Simple Saw Luv patch. Raise the Filter 1 frequency to make it sound bright and buzzy. You can use any patch that sounds very bright. Usually you will want it to be a polyphonic patch, because playing chords will make for a richer vocoder effect.
  2. Insert the vocoder: drag Effects > BV512 Digital Vocoder into the rack, just below the SubTractor, to make an insert effect. If you look at the back of the rack (press the tab key), you will see that the SubTractor connects to the vocoder’s Carrier input.
  3. Drop a sound file of someone talking (for example, the poetry readings from Assignment 4) into your sequence.
  4. In the back of the rack, connect the left Parallel output of the audio track to the Modulation input of the vocoder.

    The entire setup should look like this on the back of the rack.

  5. In the Mixer, turn down the volume for the audio track all the way. For now, you want the sound of talking to come only out of the vocoder. Later, you can mix in a bit of the dry talking by raising the channel fader for the audio track.
  6. In the Sequencer, click on the SubTractor track to enable MIDI input for it.
  7. Play the sequence while playing a long sustained chord on the synthesizer. You should hear the speech from the audio track articulating the synthesizer sound.
  8. Tweak the vocoder.
    • Try the 32-band option.
    • Use the graphic equalizer to shape the spectrum (via the Frequency Band Level Adjust sliders).
    • Turn the Shift knob to create a formant shifting effect. (This shifts the center frequencies of the bandpass filters applied to the carrier signal.)
    • Adjust the HF Emph knob to bring in a high-passed version of the dry audio track, to improve speech intelligibility.
    • Change the Attack and Decay envelope knobs to control how precisely the vocoder tracks changes in the modulator signal.
    • The Hold switch lets you halt the modulator changes, so that the filtered synthesizer sound freezes. Automating this switch can be effective.

Try substituting a rex drum loop for the audio track above. Hook the Dr. OctoRex device up to the vocoder in the same way you did for the audio track.

Copyright ©2016 Alicyn Warren, John Gibson