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By freezing the input signal you can capture a particular characteristic of the signal, which
is then imposed as a complex sustained filter shape on the Synthesis section. Here are
some examples of when this could be useful:
• If you are using a spoken word pattern as a source, the Freeze button could capture
the attack or tail phase of an individual word within the pattern—the vowel a, for
example.
• If you want to compensate for people’s inability to sustain sung notes for a long period,
without taking a breath, you can use the Freeze button. If the synthesis signal needs
to be sustained but the analysis source signal—a vocal part—is not sustained, use the
Freeze button to lock the current formant levels of a sung note, even during gaps in
the vocal part, between words in a vocal phrase. The Freeze parameter can be
automated, which may be useful in this situation.
A Short Primer on Formants
A formant is a peak in the frequency spectrum of a sound. When the term is used in
relation to human voices, formants are the key component that enables humans to
distinguish between different vowel sounds—based purely on the frequency of these
sounds. Formants in human speech and singing are produced by the vocal tract, with
most vowel sounds containing four or more formants.
Setting the Number of EVOC 20 PolySynth Filter Bank Bands
The Bands field in the Sidechain Analysis section determines the number of frequency
bands the EVOC 20 PolySynth’s filter bank uses.
The greater the number of frequency bands, the more precisely the sound can be
reshaped. As the number of bands is reduced, the source signal’s frequency range is
divided up into fewer bands—and the resulting sound will be formed with less precision
by the synthesis engine. You may find that a good compromise between sonic
precision—allowing incoming signals such as speech and vocals to remain
intelligible—and resource usage is around 10 to 15 bands.
144 Chapter 7 EVOC 20 PolySynth