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184 Chapter 14 The EVOC 20 PS
Formant Stretch
This parameter alters the width and distribution of all bands in the Synthesis filter bank,
extending or narrowing the frequency range defined by the blue bar (Low/High
Frequency parameters) for the Synthesis filter bank.
With Formant Stretch set to 0, the width and distribution of the bands in the Synthesis
filter bank is equal to the width of the bands in the Analysis filter bank. Low values
narrow the width of each band, while high values widen them. The control range is
from 0.5 to 2 (expressed as a ratio of the overall bandwidth).
Note: You can jump directly to a value of 1 by clicking on its number.
Formant Shift
Formant Shift moves the position of all bands in the Synthesis filter bank up and down.
With Formant Shift set to 0, the position of the bands in the Synthesis filter bank is
equal to the position of the bands in the Analysis filter bank. Positive values will move
the bands up in frequency, while negative values will move them down in respect to
the Analysis filter bank.
Note: You can jump directly to the values −0.5, −1, +0.5 and +1 by clicking on their
numbers.
Note: When combined, Formant Stretch and Formant Shift alter the formant structure of
the resulting vocoder sound, and can lead to some interesting timbre changes. As an
example, using speech signals and tuning Formant Shift up results in Mickey Mouse
effects.
Note: Formant Stretch and Formant Shift are also useful if the frequency spectrum of the
Synthesis signal does not complement the frequency spectrum of the Analysis signal.
You could create a synthesis signal in the high frequency range from an analysis signal
that mainly modulates the sound in a lower frequency range, for example.
Resonance