Sound Definitions

Sound effects : flanging / flanger : phasing

Phasing

Flanging is actually one specific type of phasing. In phasing, a signal is passed through one or more allpass filters which have non-linear frequency phase response. This results in phase differences in the output signal that depend on the input signal frequency. When used with multi-frequency signals like music, various frequencies in the original signal are delayed by different amounts, causing peaks and troughs in the output signal which are not in a linear harmonic series.

Flanging

By contrast, flanging relies on an overall uniform phase delay to the entire signal, which is equivalent to phasing as described above but with a filter that has a linear phase response across the frequency spectrum. The result is an output signal with peaks and troughs which are in a linear harmonic series. To put it in simpler terms, flanging results in selective but uniformly-spaced filtering of frequencies across the spectrum, whereas phasing results in selective but non-uniformly-spaced filtering of frequencies across the spectrum. Extending the comb analogy, flanging uses a comb filter with regularly-spaced teeth (like a brand new hair comb), whereas phasing uses a comb filter with irregularly-spaced teeth (like a worn hair comb with teeth that have been bent or broken).

Comparison of flanging and phasing

To the ear, flanging and phasing sound similar, yet they are recognizable as distinct colorations. Although both flanging and phasing change the delay used to create the effect over time, the effect is significantly more pronounced when using a phaser, resulting in more 'sweep' across the spectrum and more 'sparkle' or liveliness to the sound.

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