Phasing

Phasing

In the compositional technique phasing, the same part (a repetitive phrase) is played on two musical instruments, in steady but not identical tempo. Thus, the two instruments gradually shift out of unison, creating first a slight echo as one instrument plays a little behind the other, then a doubling with each note heard twice, then a complex ringing effect, and eventually coming back through doubling and echo into unison. Phasing is the rhythmic equivalent of cycling through the phase of two waveforms as in phasing. Note that the tempi of the two instruments are almost identical, so that both parts are perceived as being in the same tempo: the changes only separate the parts gradually. In some cases, especially live performance where gradual separation is extremely difficult, phasing is accomplished by periodically inserting an extra note into the phrase of one of the two players playing the same repeated phrase, thus shifting the phase by a single beat at a time, rather than gradually.

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