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Table Of Contents
86 Chapter 6 Filter
Lowest/Highest
These parameters can be found in the two small fields on either side of the Formant
Filter window. These switches determine whether the lowest and highest filter bands
are bandpass filters (just like all the bands between them), or whether they act as
lowpass/highpass filters, respectively. Click once on them to switch between the two
curve shapes available.
In the bandpass setting, the frequencies below/above the lowest/highest bands are
ignored on analysis and synthesis.
In the highpass (or lowpass) setting, all frequencies below the lowest (or above the
highest) bands will be considered for analysis and synthesis.
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.
If Formant Stretch is 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 it. The control range is from
0.5 to 2 (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, +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 result in some interesting timbre changes. As an
example, using speech signals and tuning Formant Shift up results in Mickey Mouse
effects.