A device used to remove unwanted frequencies from an audio signal
thus altering its harmonic structure. Low Pass filters are the most
common type of filter found on music synthesizers. They only allow
frequencies below the cutoff frequency to pass (Low Pass). High Pass
filters only allow the high frequencies to pass, and Band Pass filters
only allow frequencies in a selected band to pass through. A Notch
filter rejects frequencies that fall within its notch.
[From EMU Ensoniq's Glossary
of Electronic Music Terms]
