Synthetic scale

In music, synthetic scale is a scale which has been derived, often from a traditional diatonic scale such as the major scale ["Synthetic Musical Scales". Author(s): J. Murray Barbour. Source: "The American Mathematical Monthly", Vol. 36, No. 3, (Mar., 1929), pp. 155-160.] , or synthesized and from which further pitch collections may be derived. These synthetic combinations of notes arranged in the pattern of a scale often serve, or can theoretically be considered to serve, as the basic melodic and/or harmonic material for a passage of music. It could be almost any combination of such notes that a composer chooses, although a few synthetic scales have become relatively popular, and some have acquired names of their own.

Examples include the whole tone and octatonic scales, the Lydian dominant scale, any of Olivier Messiaen's 7 Modes of limited transposition, the scale derived from Alexander Scriabin's mystic chord, and the Hungarian Minor and Double Harmonic scales (which are different modes of the each other).

The term is less applied to the standard pentatonic scale, since it is just a subset of an ordinary major scale or Ionian mode, although it could with some justification be regarded as a type of synthetic scale, since the smaller number of available notes does result in the scale being treated more in the manner of a synthetic scale than a traditional major scale. This is largely because the defining characteristic of a major scale, the dominant 7th chord, is not available in the pentatonic scale, which forces the composer to treat the scale material in other ways which more resemble the treatment often used in synthetic scales - that is, forming chords out of available notes combined in unorthodox ways (from the point of view of traditional major or minor keys).

Note that some synthetic scales are derived from very ancient folk-music idioms, and, despite the literal meaning of "synthetic", it does not necessarily imply that the scale in question has been artificially designed by the composer (although sometimes it has been). Other synthetic scales, such as the octatonic, have grown naturally from the increasing chromaticism of late-19th-century music, and came to be regarded as a new scale in their own right. For instance, the octatonic scale probably evolved from increasing decorations of an ordinary diminished-7th chord, which has been a standard chord from before the time of J. S. Bach. Regardless of these varying origins of synthetic scales, some synthetic in the literal sense and some not, the basic meaning of "synthetic scale" is just that of a scale other than an ecclesiastical mode or a major or minor scale, and, because of its difference from a major or minor scale, requiring non-traditional treatment to some degree.

Many jazz composers and 20th-century classical composers have written parts of compositions, or even occasionally entire compositions, based on one or more synthetic scales. Scriabin was particularly noted for doing this in the latter half of his career, and was one of the first composers to do this extensively - and, contrary to comments often read in reviews or commentaries, he used a range of different scales, and did not always use the one scale derived from his mystic chord. The all-too-often-repeated claim (sometimes by reputable commentators one would think would know better) that Scriabin's late music is based on his mystic chord or Prometheus scale is grossly oversimplified, if not downright untrue, as an examination of a range of his later scores will clearly show: his mystical chord is actually somewhat rare in his music, other than in "Prometheus: The Poem of Fire" - and even then, it rarely appears in the exact arrangement so often seen in articles about Scriabin's harmony, arranged all in 4th intervals.

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