glossary
Filter slope tells you how rapidly level falls as frequency moves beyond the cutoff.
A 12 dB-per-octave low-pass filter reduces level by roughly another 12 dB each time frequency doubles beyond its cutoff. A high-pass filter applies the same idea as frequency halves below cutoff.
Common slopes include 6, 12, 18, 24, and 48 dB per octave, though the exact curve also depends on the filter design.
A gentle slope removes less nearby material and can sound natural. A steep slope isolates more aggressively but may create stronger phase rotation or resonance near the cutoff.
The cutoff label alone does not describe how much audible content the filter removes.
Set the cutoff while the full mix plays, compare nearby slopes, and watch whether the filter changes peak level or headroom. Use the least aggressive curve that solves the problem.
Meter Core helps keep spectral cleanup connected to level and headroom after the filter.