This is a particular type of filter mode where audio frequencies or harmonics around the corner or cutoff frequency setting are removed, nor “notched out” of the overall spectrum. It is the opposite of a bandpass filter, which only passes harmonics around the cutoff frequency. Notch filters tend to have a subtle effect on the sound; moving (modulating) the cutoff frequency can result in a weak phasing sort of sound.
Notch filters are often used in sound systems to weaken or remove a problematic frequency, such as ground loop hum, a resonance in a room, or other annoying peak in the harmonic spectrum of a sound. Think of using a notch filter in a patch to hollow out a sound, leaving room in the harmonic spectrum for other sounds to exist with less competition, or just to create a sound more likely to catch the ear because something that is expected is instead missing.« Back to Glossary Index