Phase Cancellation
Definition
The reduction or elimination of audio signal that occurs when two signals with similar content are combined out of phase. When two identical signals are 180° out of phase, they cancel completely. Partial phase cancellation causes tonal thinning and comb filtering.
In Simple Terms
When two similar signals combine out of sync and partially erase each other, making the sound thinner, weaker, or hollow. It's especially common with multiple microphones on drums or guitar cabinets. Flipping the phase button often fixes it instantly.
In Practice
A kick drum microphone placed inside the kick and another outside, combined without phase correction, exhibit partial phase cancellation — the kick loses body and punch because the two signals partially cancel each other's low frequencies.