Frequency Masking
Definition
A psychoacoustic phenomenon where one sound obscures another when they occupy the same or adjacent frequency ranges. In mixing, frequency masking between instruments causes elements to lose clarity and definition, requiring EQ and arrangement decisions to create separation.
In Simple Terms
When two instruments share the same frequency range, they fight each other and both become unclear — like two people talking at the same time. EQ one down where the other lives, and both suddenly become audible.
In Practice
A bass guitar and a kick drum both have significant energy at 80–100 Hz. Without EQ or sidechain treatment, they mask each other, resulting in a muddy, undefined low end. Carving complementary frequency shapes allows both to be heard clearly.