Sound Definitions

Sound effects : phaser / phasing

A phaser is an audio signal processor used to filter a signal by attenuating a series of "notches" in the frequency spectrum. The position of the notches typically varies over time (modulation), phasers usually include a low frequency oscillator for this purpose. A stereo phaser is usually two identical phasers modulated by a quadrature signal, i.e., the output of the oscillators for the left and right channels are a quarter-wave out of phase.

Phasers past and present

Traditional electronic phasers use a series of variable all-pass phase-shift networks and mix the output with the dry (unprocessed) signal, additionally, the output can be fed back to the input to create a more intense effect. Most modern phasers are a part of a digital signal processor, often trying to emulate analogue phasers. Phasers are mostly found as plugins for sound editing software, as a part of a monolithic rackmount sound effect unit, and as "stompbox" guitar effects.

A flanger is a type of phaser where the notches are uniformly spaced, in particular, where the notches are created by mixing the signal with a delayed version of a signal. Flangers tend to sound more natural, like the "jet plane whoosh" effect, whereas Phasers tend to sound more alien.

Uses of phasing

• Phasing is often used to make a natural sound seem artificial, such as making a human voice sound like a computer or robot voice. A phaser was used on C-3PO's voice in Star Wars, for example.
• Phasing is a popular effect for electric guitar. Eddie Van Halen often used a phaser as part of his signal chain, after his distortion effects, including the amplifier itself: Van Halen used a power attenuator to bring the amp's output down to line level so he could put effect boxes after it.

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