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Chapter 8 EVOC 20 PolySynth 137
EVOC 20 PolySynth analysis parameters
The parameters in the Sidechain Analysis section control how EVOC 20 PolySynth analyzes
and uses the input signal. Be precise with these parameters to attain the best possible speech
intelligibility and the most accurate tracking.
Sidechain analysis parameters
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Attack knob: Rotate to determine how quickly each envelope follower—coupled to each
analysis lter band—reacts to rising signal levels. Longer attack times result in a slower
tracking response to transients—level spikes—of the analysis input signal. A long attack time
on percussive input signals—a spoken word or hi-hat part, for example—will translate into
a less articulated vocoder eect. Set the Attack parameter to the lowest possible value to
enhance articulation.
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Release knob: Rotate to determine how quickly each envelope follower—coupled to each
analysis lter band—reacts to falling signal levels. Longer release times cause the analysis
input signal transients to sustain for a longer period at the vocoder’s output. A long release
time on percussive input signals—a spoken word or hi-hat part, for example—will translate
into a less articulated vocoder eect. Use of extremely short release times results in rough,
grainy vocoder sounds. Release values of around 8 to 10 milliseconds are useful starting points.
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Freeze button: Turn on to hold—or freeze—the current analysis sound spectrum indenitely.
When Freeze is enabled, the analysis lter bank ignores the input source, and the Attack and
Release knobs have no eect.
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Bands eld: Drag to set the number—up to 20—of frequency bands used by the lter banks.
Freeze the input signal
Freezing the input signal lets you capture a particular characteristic of the signal, which is then
imposed as a complex sustained lter shape on the Synthesis section. Here are some examples
of when this could be useful:
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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.
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People cannot sustain sung notes indenitely. To compensate for this human limitation,
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.
m Click the Freeze button to hold, or sustain, the sound spectrum of the analysis input signal.