In the compositional technique phasing, popularized by composer Steve Reich, the same part (a repetitive phrase) is played on two musical instruments, in steady but not identicaltempo. 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.
A very basic example, using the adding elements technique (in this case a pause between repeats by one of the players):
I love Steve Reich! If you want a really crazy example of phasing, check out his early (like late 60s) experiment with vocal sampling, "Come Out." It's perhaps best known for a sample on the Madvillain track "America's Most Blunted."
Posted by: Jason Grote | July 17, 2009 at 08:36 AM