The phaser, or phase shifter, is closely related to the flanger in that it also works by sweeping notches through the spectrum of the input signal. While the term phasing is sometimes used synonymously with flanging [#!Bartlett70!#], commercial phase shifters have been observed to implement nonuniformly spaced notches.4 We will therefore define a phaser as any linear filter which modulates the frequencies of a set of non-uniformly spaced notches, while a flanger will remain any device which modulates uniformly spaced notches.