''Tonality flux'' is

Harry Partch Harry Partch (June 24, 1901 – September 3, 1974) was an American composer, music theorist, and creator of unique musical instruments. He composed using scales of unequal intervals in just intonation, and was one of the first 20th-century co ...

's termPartch, Harry (1949). ''

Genesis of a Music ''Genesis of a Music'' is a book first published in 1949 by microtonal composer Harry Partch (1901–1974). Partch first presents a polemic against both equal temperament and the long history of stagnation in the teaching of music; according ...

'', p.188-190. Da Capo Press . for the kinds of subtle

harmonic A harmonic is a wave with a frequency that is a positive integer multiple of the '' fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', ...

changes that can occur in a

microtonal Microtonal music or microtonality is the use in music of microtones— intervals smaller than a semitone, also called "microintervals". It may also be extended to include any music using intervals not found in the customary Western tuning of t ...

context from notes moving from one

chord Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...

to another by tiny increments of

voice leading Voice leading (or part writing) is the linear progression of individual melodic lines ( voices or parts) and their interaction with one another to create harmonies, typically in accordance with the principles of common-practice harmony and count ...

. For instance, within a

major third In classical music, a third is a musical interval encompassing three staff positions (see Interval number for more details), and the major third () is a third spanning four semitones. Forte, Allen (1979). ''Tonal Harmony in Concept and P ...

G-B, there can be a

minor third In music theory, a minor third is a musical interval that encompasses three half steps, or semitones. Staff notation represents the minor third as encompassing three staff positions (see: interval number). The minor third is one of two com ...

G to B, such that in moving from one to the other each line shifts less than a half-step. Within a

just intonation In music, just intonation or pure intonation is the tuning of musical intervals as whole number ratios (such as 3:2 or 4:3) of frequencies. An interval tuned in this way is said to be pure, and is called a just interval. Just intervals (and ...

scale, this could be represented (, indicates an approximate quarter-tone sharp, an approximate quarter-tone flat) by moving to like so: One voice slides down from 386 cents to 347, the other slides up from 0 cents to 32, yet the harmonic shift can be dramatic. The best-known example of tonality flux, and one of the two Partch uses as illustration, is the beginning of his composition ''The Letter'', in which the

kithara The kithara (or Latinized cithara) ( el, κιθάρα, translit=kithāra, lat, cithara) was an ancient Greek musical instrument in the yoke lutes family. In modern Greek the word ''kithara'' has come to mean "guitar", a word which etymologi ...

alternates between two chords, one major and one

minor Minor may refer to: * Minor (law), a person under the age of certain legal activities. ** A person who has not reached the age of majority * Academic minor, a secondary field of study in undergraduate education Music theory *Minor chord ** Bar ...

, with the minor third of one nestled inside the major third of the other (given here in Ben Johnston's pitch notation): In this notation, which assumes G as the tonic or 1/1, a 7 lowers a pitch from a

value by 35/36, or 48.77 cents; an upside-down 7 raises a pitch by the same amount. The first chord is a major triad and, relative to G, contains the notes 8/7 (231 cents above G), 10/7 (617 cents), and 12/7 (933 cents); the second chord is a minor triad comprising the pitches 7/6 (267 cents), 7/5 (583 cents), and 7/4 (969 cents). Notice that while the outer notes ascend from the first chord to the second, the middle note descends. Such subtle movements were among the attractions that Partch found in an expanded just intonation of more than 12 pitches per octave. Tonality flux is a special instance of the principle of parsimonious (most direct) voice leading.

References

{{Musical tuning Harry Partch Musical tuning Voice leading

See also

References