Flanging

The definition for flanging is identical to phasing: a steady or variable cancellation of frequencies created when two copies of identical program material are combined with small variations in timing. For all practical purposes, the terms are interchangeable.

The difference between phasing and flanging is subjective and relates to the use of these terms in processing electric or electronic music. Phasing typically refers to shorter timing errors, up to 1/2 a video frame, (16ms). Shorter timing errors affect shorter audio wavelengths, which cause cancellation in the higher frequencies of the program material. Flanging typically refers to longer timing errors, 1/2 to approximately 2 video frames, (16ms to 66ms), which cause cancellation in the lower frequencies of program material. When the timing difference reaches 2 frames and beyond, the anomaly will be perceived as separate events, and this is known as echo.

The swishing effect heard in this clip moving up and down in pitch behind the dialog is the sound of flanging audio.