Phasing

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In minimal music , phasing (also called phase shifting) describes a composition technique in which two instruments perform the same, often repetitive voice , one playing at a steady tempo , while the other moves with increasing distance before the first. The two voices are initially "out of phase " and gradually "in phase" again ( phase shift ). Both voices are felt to be played at the same tempo; only aural and rhythmically variable auditory impressions result.

Example of rhythm phases with 16 voices: The first part of the voices plays the rhythm (half note, quarter note, half note, quarter note) and the other voices play the same rhythm 101% faster ... 102%, 103% ..., 115%. Played in overtones: The first eight voices play the first eight overtones, and the second eight voices play the same overtones, transposed an octave lower.
Visualization of the phase shift with two rollers sharing an identical pattern on a common spool. This pattern can be contrasted with itself at all positions by rotating one of the discs.

Generation and Effect

generation

Due to the phase shift, the two instruments gradually shift out of harmony and first produce a slight echo, if one instrument plays a little in a row, then a doubling effect, with each note being heard twice, then a complex ringing effect and finally by doubling and echoing back in unison . Phase adjustment is the rhythmic equivalent of stepping through the phase of two waveforms as in phase adjustment. The tempi of the two instruments are only almost identical (objectively not), so that both parts are perceived subjectively as being at the same tempo: The changes only separate the parts gradually. In some cases, especially in live performances where gradual separation is extremely difficult, phasing is achieved by periodically inserting an extra note (or temporarily removing one) from the phrase of either player playing the same repeated phrase, whereby the phase is shifted minimally.

effect

The effect is similar to that heard when a shortwave transmitter is faded out. Since the signal takes several paths through the ionosphere, the different time delay means that the signal has the characteristic phase sound.

Pioneering work

Discovery as an electroacoustic effect

An early example of electro-acoustic phase music is Earle Brown's " Music for the Stadler Gallery " (1964). The work contained four recordings of the same instrumental piece, which were played continuously with four separate tape recorders. Over time, the recordings got increasingly out of phase.

In 1965, influenced by Terry Riley's use of tape loops and delays, the American composer Steve Reich began experimenting with tape loop techniques. Reich was involved in the world premiere of Riley's "In C" and suggested the use of the eighth pulse, which is now the standard for the performance of the piece. During his experiments, the American composer Steve Reich made a momentous discovery: He found that tape loops with exactly the same musical material on two different tape recorders never ran exactly in sync, but gradually got "out of phase". The result of the time shifting of the recordings was a transformation process in which different timbres, beats and overtones could be heard. Some of these sounded significantly different from the original segment of the recorded material. If the sound source had a natural cadence, the phase shift caused incremental changes in the perceived rhythm as the material drifted in and out of phase. Using additional tracks and loops with identical source material expands the possibilities for creating a wider range of phase relationships.

In discussing the technical aspects of what is known as a "phase shifting process", Reich notes that it is related to the infinite canon, or ring canon, in medieval music . The difference between phase music and traditional ring canons, in which two or more identical melodies are played one after the other, is that the melodic phrases are usually short repetitive patterns and the imitation is not fixed but variable.

Reich recognized the potential for a gradual phase shift as a compositional approach. This process of gradual phase shifts gave birth to so-called minimal music. For Steve Reich, it became the central compositional approach in all of his early work. However, it is also stated that the technique has origins in Henry Cowell's " New Musical Resources" and in Tempo studies by Conlon Nancarrow .

Transferred to a composition with instruments

The technology started in the " Tape Music " of the composer Steve Reich, in which several copies of the same tape loop are started simultaneously on different tape recorders. Over time, the small differences in tape speed create a " flanger " effect and a rhythmic separation. From 1965, Reich began to research the gradual phase shift in the context of composed music for instruments.

Composed phase music consists of two or more instruments playing a repetitive phrase (part) at a steady, but not identical, tempo. With a gradual phase shift, the tempo of the various instruments is initially almost identical, so that both parts are perceived as sounding in unison and at the same tempo. Over time, the phrases gradually shift, initially creating a slight echo when an instrument plays a little in a row. This is followed by what sounds like a doubling with each note heard twice. The next thing is a complex ringing effect, after which the phrases finally return to an in-phase position by doubling, echoing and unison.

A number of the perceived changes, both in phrasing and timbre, that result from this phasing process are psychoacoustic in nature. According to Steve Reich, in this way the listener notices a pattern in the music in which the ear picks up sounds that sound as a continuous overall structure of sounds or as a texture.

Use of the phase shift in the composition

First uses

Steve Reich uses the phase technique for the first time on a trial basis for the score for Robert Nelson's short film "Oh dem Watermelsons". Reich's compositions " Come Out " (1966) and " It's Gonna Rain " (1965) were created using a phase shift. In 1967 he used the phase technique, transferred to live instrumental music, in the roughly 20-minute key work " Piano Phase " (1967). It consists of transformations of the first six notes of the A major scale. " Drumming " (1970-1971) was also created according to this pattern. Later, the phase change was more immediate than gradual, that is, it was carried out gradually instead of gradually, as in Reich's " Clapping Music " (1972).

Further development

With Music for 18 Musicians (1974–1976), Reich was able to differentiate the phasing process and transfer it to an ensemble: By using several instruments, Steve Reich achieved highly complex grids from a wide variety of rhythmic structures.

Reception of the compositional approach

John Luther Adams used the technique in the orchestral piece " Dream in White on White " (1992). The US composer William Ervin Duckworth used them for the piano piece "The Time Curve Preludes " (1977-78).

An example from popular music is " The True Wheel " on Brian Eno 's album " Taking Tiger Mountain (By Strategy) ".

Playing repetitive phases with the same tempo but different metric lengths (beats per measure), as in the music of Philip Glass and others, is not phasing but can be viewed as polyrhythmic .

Individual evidence

  1. ↑ a b c d Kyle Gann: Minimal Music, Maximal Impact. In: https://nmbx.newmusicusa.org/ . New Music USA, November 1, 2001, accessed December 9, 2019 .
  2. ↑ Resident Advisor: Steve Reich. In: https://www.residentadvisor.net/ . Resident Advisor, 2011, accessed December 7, 2019 .
  3. ^ Wim Mertens: American Minimal Music: La Monte Young, Terry Riley, Steve Reich, Philip Glass . Pro / Am Music Resources, 1988, ISBN 978-0-912483-15-3 , pp. 50 f .
  4. ↑ Alex Ross: The Rest is Noise . 2nd Edition. Piper Verlag, Munich 2009, ISBN 978-3-492-05301-3 , pp. 552 f .