Filter
Definition
A circuit or algorithm that removes or attenuates specific frequency ranges from an audio signal. Common types include high-pass, low-pass, band-pass, and notch filters.
In Simple Terms
Removes certain frequencies from a sound. A high-pass filter cuts the rumble below a certain point; a low-pass filter removes the harshness above. Basic but essential for cleaning up any mix.
In Practice
A low-pass filter on a synthesizer pad removes high-frequency content to create a warmer, darker texture in the mix.
Common Confusion
A filter is not the same as an EQ band. An EQ band is a filter, but EQs typically combine multiple filters with gain control. A standalone "filter" effect (in synths and modulation effects) is usually a sweepable HPF/LPF without gain — it removes or passes frequencies but cannot boost them.
Sources & Verification
- Bristow-Johnson, R. — Audio EQ Cookbook (biquad filter formulas)W3C
- Smith, J. O. — Introduction to Digital Filters with Audio ApplicationsStanford CCRMA, 2007
Last verified: 2026-05-05