How to Make Your Sound Sing with Vocoders
Pages: 1, 2, 3, 4, 5

The next example uses the same Reason patch, but with vocals instead of drums as the speech input. Here's the raw vocal, a quote from Chapter 3 of Nicholas Nickleby, by Charles Dickens:

• Raw Vocal (212KB MP3)

In the tutorial file OreillyVocoderDemo1.rns, I've loaded the original WAV file containing the speech into a Reason NN-XT sampler. The carrier signal comes from a Reason SubTractor synth playing a basic sawtooth patch. The Reason Vocoder is set to 32-band mode. (Turn the Band Count knob to compare the other settings.) Here's the result:

• Vocal as Speech Input (224KB MP3)

Fig. 5. In tutorial file 2, the yellow cable carries the output of vocoder band 10 to the pan-control input on the mixer. As the output level changes, the sound moves left and right in the stereo field. (Click to enlarge.)

Some vocoders let you shift the frequencies of either the speech or carrier bandpass filters up or down. In some cases that will make the output more intelligible. It can also shift the vocal formants (the characteristic resonant frequencies of the human mouth and nasal passages) up or down. The result is perhaps less distinctive than formant-based pitch-shifting, but the technique can be useful. In the next example (which I created in the song file OreillyVocoderDemo2.rns), I played the speech sample down an octave, thus stretching it to twice its original length. (See Figure 5.) I then used the Reason vocoder's Shift knob to move the formants back up into the expected range. If you listen closely, you may also hear that one of the envelope-follower outputs is modulating the stereo pan position of the audio:

• Transposition Becomes Time-Stretch (432KB MP3)

Some vocoders give you the option of repatching the envelope followers to arbitrary carrier bands. This will render the words in the speech input unintelligible, but the output can still have an expressive character. This technique is illustrated (perhaps badly) in OreillyVocoderDemo3.rns (See Figure 6). The vocal sample is the same as in the first two examples, though only the beginning of it is played, in a stuttering manner:

• Repatching Envelope Followers (248KB MP3)

Fig. 6. In tutorial file 3, I cross-patched the envelope follower outputs to create a stuttering sound.