Flanging originates from the technique of pressing a finger against the flange of a tape reel to slow it down, causing the playback to phase against a second copy. The resulting sound — a sweeping, metallic resonance — is caused by comb filtering where the null frequencies continuously shift as the delay time changes. When the delay is very short (0-3 ms), the effect is perceived as "phasing." Longer varying delays (3-15 ms) produce the classic flanging effect.

The comb filter created by flanging follows a predictable pattern: nulls occur at frequencies where the delay equals an odd multiple of half-periods, and peaks occur where the delay equals whole-period multiples. As the delay sweeps, these nulls and peaks move up and down the frequency spectrum, creating the characteristic animated tonal quality.

In live sound reinforcement, unintentional flanging is a serious problem indicator. When two loudspeakers reproduce the same signal with a small, varying time offset — perhaps due to environmental factors like temperature changes affecting sound speed, or structural vibration causing speaker movement — listeners experience flanging as a wavering, hollow quality. This is distinct from static comb filtering, which produces fixed coloration.

SonaVyx detects flanging-related issues through multiple tools. The problem detector's comb filter analysis identifies the periodic null pattern characteristic of time-offset interference. The transfer function measurement reveals the comb filter pattern directly in the frequency response. Phase response analysis shows the linear phase slope that indicates a pure delay. The AI diagnostic can identify flanging patterns and recommend time alignment corrections to eliminate the sweeping comb filter effect.