The parameters in the Sidechain Analysis section control how the input signal is analyzed and used by the EVOC 20 PolySynth. You should be as precise as possible with these parameters to ensure the best possible speech intelligibility and accurate tracking.
The Freeze button in the Sidechain Analysis section of the EVOC20 PolySynth freezes the sound spectrum of the analysis input signal.
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.
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.