User`s manual

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Frequency. Also, note that the Lower and Upper Transition Slopes always have
different values; this is because the frequency width of an octave is proportional
to Cutoff Frequency.
Stopband Specifies amount in dB by which frequencies
Attenuation: above the Lower Cutoff Frequency and below the Upper Cutoff Frequency are
attenuated. Stopband attenuation is adjustable from 0dB to 90dB in 1 dB steps.
A graphical description of the Bandstop filter and its controls follows in the figure below.
Figure 7-9: Bandstop Filter Graphical Description
7.6 Comb Filter
Application:
The Comb filter is used to remove, or "notch out", harmonically related noises (noises which
have exactly equally-spaced frequency components), such as power-line hum, constant-speed
motor/generator noises, etc., from the input audio. The filter response consists of a series of
equally-spaced notches which resemble a hair comb, hence the name "Comb filter".
Adjust the Fundamental Notch Frequency to the desired spacing between notches (also known
as "fundamental frequency"). Set the Notch Limit to the frequency beyond which you do not want
any more notches. Set the Notch Depth to the amount in dB by which noise frequency
components are to be reduced.
Normally, the Notch Harmonics option will be set to All, causing frequencies at all multiples of the
Fundamental Notch Frequency (within the Notch Limit) to be reduced. However, certain types of
noises have only the odd or even harmonic components present. In these situations, set the
Notch Harmonics option to either Odd or Even.
Figure 7-10: Comb Filter Control Window
Description of controls is as follows:
Fundamental Specifies fundamental frequency in Hertz of
Notch comb filter.Notches are generated at multiples,
Frequency or harmonics, of this frequency.