Apply a two-pole Butterworth band-reject filter with central frequency frequency, and (3dB-point) band-width width. The filter roll off at 6dB per octave (20dB per decade).

The filter accepts the following options:

frequency, f

Set the filter’s central frequency. Default is 3000.

width_type

Set method to specify band-width of filter.

h

Hz

q

Q-Factor

o

octave

s

slope

width, w

Specify the band-width of a filter in width_type units.