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Table Of Contents
74 Chapter 6 Filter
Note: Increasing the number of bands also increases the processor overhead.
High/Low Frequency
The blue bar shown just beneath the EVOC label is a multi-part control which is used to
determine the lowest and highest frequencies allowed to pass by the filter. Frequencies
which fall outside these boundaries will be cut. All filter bands are distributed evenly
across the range defined by the High/Low Frequency values.
To adjust the Low Frequency value, simply click-hold on the silver slider to the left of
the blue bar, and drag to the right (or left). The value range is 75–750 Hz.
To adjust the High Frequency value, simply click-hold on the silver slider to the right
of the blue bar, and drag to the left (or right). The value range is 800–8000 Hz.
To adjust both sliders simultaneously, click on the area between the slider halves
(directly on the blue bar) and drag to the left or right.
You can make changes to the High/Low Frequency values directly by using your
mouse as a slider on the numerical entries—80 and 8000 Hz in the diagram.
Lowest/Highest
These parameters can be found in the two small switches on either side of the Formant
Filter window. These switches determine whether the lowest and the 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.
In the Highpass or Lowpass setting, all frequencies below the lowest (or above the
highest) bands will also be treated.
Slope
The pull-down menu Slope determines the amount of filter slope applied to all filters of
both filter banks. Choices are 1 (filter attenuation of 6 dB/Oct.) and 2 (filter attenuation
of 12 dB/Oct.): 1 sounds softer, 2 sounds tighter.
Boost A/B Controls
The Boost A and Boost B knobs allow an increase or cut in the overall gain of the A and
B filter banks. Their range is
±
20 dB. To adjust, click-hold and drag up or down with the
mouse.
Note: You will need these controls, as the filter bank achieves its sounds by turning
down the level of one or more filter bands. To make up for the resulting energy loss,
use Boost.