Microtonal music is music using microtones — intervals of less than an equally spaced semitone. Microtonal music can also refer to music which uses intervals not found in the Western system of 12 equal intervals to the octave.
The Hellenic civilizations of ancient Greece also left fragmentary records of their music—c.f., the Delphic Hymns. The ancient Greeks approached the creation of different musical intervals and modes by dividing and combining tetrachords, recognizing three genera of tetrachords: the enharmonic, the chromatic, and the diatonic. Ancient Greek intervals were of many different sizes, including microtones. The enharmonic genus in particular featured intervals of a distinctly "microtonal" nature, which were sometimes smaller than 50 cents, less than half of the contemporary Western semitone of 100 cents. In the ancient Greek enharmonic genus, the tetrachord contained a semitone of varying sizes (approximately 100 cents) divided into two such smaller, microtonal, intervals; in conjunction with a larger interval of roughly 400 cents, these intervals comprised the perfect fourth (approximately 498 cents, or the ratio of 4/3 in just intonation) (West 1992, 160–72).
Joel Mandelbaum has argued in his PhD thesis that scholarship done on the Antiphonarium Codex Montpellier suggests that it records microtonal tunings, probably the Greek enharmonic (Mandelbaum 1961, ). In his opinion, this indicates that microtonal tunings survived and were commonly used late into the medieval period.
Meantone tunings date from the early 1490s, as scholars such as Richard Taruskin and Patrizio Barbieri have pointed out. Since the time of Pietro Aron's treatise (Aron 1523), meantone tuning became extremely common and was considered to represent "correct" tuning throughout Europe until 1750 and in England and Spain until 1850. Such meantone tunings sound similar to, but more harmonious than, conventional Western tunings of 12 equal pitches per octave, when performed on an instrument limited to 12 pitches per octave, as long as the composer restricts him/herself to a narrow compass of musical keys close to the root note of the tuning (i.e., if the meantone tuning is tuned starting with C, the keys close to C major will sound like a more harmonious take on conventional Western music; distant keys, however, like Eb minor, will contain highly audibly exotic and sometimes discordant musical intervals.) Some early composers, however, deliberately wandered far afield from the root note of meantone tunings, producing highly microtonal effects in typical renditions of their music. One prominent example is "Ut, Re, Mi, Fa, Sol, La" by the British virginal composer John Bull (composed sometime between the 1580s and 1610, and included in the Fitzwilliam Virginal Book). Such extensive modulation in meantone tuning on a 12-note-per octave instrument sounds "wolf" fifths and other exotic musical intervals not found in contemporary Western music using 12 equal pitches per octave.
It was quite common in the heyday of meantone tuning to find keyboards with "split" keys or special organ stops, often allowing 13-16 pitches per octave of meantone tuning. In this way music by Handel and many other composers could be played in meantone tuning, maintaining smooth harmony and conventional-sounding melody even as the music modulated to distant keys. Teachers of string instruments, including Leopold Mozart, and of wind instruments, including Quantz, expected their students to distinguish all enharmonic pairs of pitches (like F# and Gb) in their playing, with the sharpened version of one diatonic tone being played lower than the flattened version of the next diatonic tone up. So composers in the meantone era who restricted their harmonic compass were doing so largely because they were writing for keyboard or an ensemble that included a keyboard.
Many tunings of meantone temperament can be made to close, in practice, using a manageable number of notes per octave. The 1/3-comma and 1/4-comma meantones close very nearly in 19 and 31 tones per octave, respectively, with better approximations to the 5-limit thirds and sixths of the diatonic scale than can be found on modern 12-tone instruments. Several French composers of the 17th century made use of this fact by designing keyboards for 19 equal intervals to the octave, which could be played in all keys with no "wolf" intervals. 17th-century Dutch scientist and musician Christiaan Huygens promoted the use of 31-equal, which also allows meantone in all keys without "wolves", but with better approximations of 7-limit intervals than in 19-equal. Huygens advocated the use of the just seventh, with pitch ratio 7/4. This interval is very well approximated in 31-equal. In the 20th century, a Dutch school of microtonalists arose around Adriaan Fokker, which sought to use the novel resources of Huygens' 31-tone system as fundamental features of new musical forms, and not merely according to their established functions in common-practice tonality. Many Dutch composers were associated with this school, including Fokker himself under a pseudonym; the best-known was probably Henk Badings.
Guillaume Costeley's "Chromatic Chanson", "Seigneur Dieu ta pitié" of 1558 used 1/3 comma meantone and explored the full compass of 19 pitches in the octave, making use of audibly microtonal intervals like the 63-cent interval of 1/19 of an octave.
The Italian Renaissance composer and theorist Nicola Vicentino (1511-1576) experimented with microintervals and built a keyboard with 36 keys to the octave, known as the archicembalo. However Vicentino's experiments were primarily motivated by his research (as he saw it) on the ancient Greek genera, and by his desire to have beatless intervals (when played with near-harmonic-series timbres) available within chromatic compositions.
Johann Kuhnau's composition "Der Kampf zwischen David und Goliath," composed around 1700 in meantone, makes prominent and aggressive use of the exotic intervals available in meantone—specifically, the "wolf" fifth. The effect of contrasting lightly tempered fifths with the dissonant "wolf" fifth depends on the audible microtonal distinction between the intervals.
Composers such as Beethoven and Schubert made extensive use of the enharmonic modulation cycles possible only in a closed tuning of 12 pitches per octave, and not open-ended tunings like meantone. This led to the demise of meantone thinking in most of Europe by the outset of the Romantic period. Microtonality was not completely lost, however, as some string teachers began to advocate "expressive intonation" in which the enharmonic distinctions of meantone were often reversed, i.e., the sharpened version of one diatonic tone often played higher than the flattened version of the next diatonic tone up.
Jacques Fromental Halévy composed a quarter-tone work for soli, choir and orchestra "Prométhée enchaîné" in 1849, and European composers produced an ever-increasing number of microtonal compositions as the 19th century waned and the 20th century began.
By the 1910s and 1920s, a fad emerged for quarter tones (24 equal pitches per octave), inspiring composers as Charles Ives, Julián Carrillo, Alois Hába, Ivan Wyschnegradsky, and Mildred Couper. Such was the popularity of 24 equal during the late teens and 1920s, for example, that Erwin Schulhoff gave classes in quarter-tone composition at the Prague Conservatory. Béla Bartók came late, and only sporadically, to quartertones (e.g. in his Sonata for violin solo, which uses quarter tones in an essential manner).
Alexander John Ellis, who in the 1880s produced a translation with extensive footnotes and appendices to Helmholtz's On the Sensations of Tone, proposed an elaborate set of exotic just intonation tunings and non-harmonic tunings (Helmholtz 1885, 514–27). Ellis also studied the tunings of non-Western cultures and, in a report to the Royal Society, determined that they did not use either equal divisions of the octave or just intonation intervals (Ellis 1884). Ellis inspired Harry Partch immensely (Partch 1979, vii).
During the Exposition Universelle of 1889, Claude Debussy heard a Balinese gamelan performance and was exposed to their non-Western tunings and rhythms. Some scholars have ascribed Debussy's subsequent innovative use of the whole-tone (6 equal pitches per octave) tuning in such compositions as the Fantaisie for piano and orchestra and the Toccata from the suite Pour le piano to his exposure to the Balinese gamelan at the Paris exposition (Lesure 2001), and have asserted his rebellion at this time "against the rule of equal temperament" and that the gamelan gave him "the confidence to embark (after the 1900 world exhibition) on his fully characteristic mature piano works, with their many bell- and gong-like sonorities and brilliant exploitation of the piano’s natural resonance" (Howat 2001). Still others have argued that Debussy's works like L'Isle joyeuse, La Cathédrale engloutie, Prélude à l'après-midi d'un faune, La Mer, Pagodes, Danseuses de Delphes, and Cloches à travers les feuilles are marked by a more basic interest in the microtonal intervals found between the higher members of the overtone series, under the influence of Hermann Helmholtz's writings (Don 1991, 69 et passim). Berliner's introduction of the phonograph in the 1890s allowed much non-Western music to be recorded and heard by Western composers, further spurring the use of non-12-equal tunings.
While experimenting with his violin in 1895, Julian Carrillo (1875-1965) discovered the sixteenths of tone, i.e., sixteen clearly different sounds between the pitches of G and A emitted by the fourth violin string. He named his discovery Sonido 13 (the thirteenth sound) and wrote on music theory and the physics of music. He invented a simple numerical musical notation that can represent scales based on any division of the octave, like thirds, fourths, quarters, fifths, sixths, sevenths, and so on (even if Carrillo wrote, most of the time, for quarters, eights, and sixteenths combined, the notation is able to represent any imaginable subdivision). He invented new musical instruments, and adapted others to produce microintervals. He composed a large amount of microtonal music and recorded about 30 of his compositions.
Major microtonal composers of the 1920s and 1930s include Alois Hába (quarter tones, or 24 equal pitches per octave, and sixth tones), Julian Carillo (24 equal, 36, 48, 60, 72, and 96 equal pitches to the octave embodied in a series of specially custom-built pianos), Ivan Wyschnegradsky (third tones, quarter tones, sixth tones and twelfth tones, non octaving scales) and the early works of Harry Partch (just intonation using frequencies at ratios of prime integers 3, 5, 7, and 11, their powers, and products of those numbers, from a central frequency of G-196) (Partch 1979, chapt. 8, "Application of the 11 Limit", 119–37).
Prominent microtonal composers or researchers of the 1940s and 1950s include Adriaan Daniel Fokker (31 equal tones per octave), Partch again (continuing to build his handcrafted orchestra of microtonal just intonation instruments) and Ivor Darreg (who built the first fully retunable electronic synthesizer capable of any division of the octave, just or equal or non-just non-equal).
Prominent microtonal composers of the 1960s and 1970s include John Eaton (who created his own microtonal synthesizer, the Syn Ket, to produce microtonal intervals), Ivor Darreg again (who augmented his home-built orchestra of instruments to include guitars refretted in equal temperaments 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, and 31, as well as the magalyra series of sub-contrabass steel guitar instruments), Harry Partch, Easley Blackwood (who composed and performed the well-known Twelve Microtonal Etudes for Electronic Music Media with compositions in every equal division of the octave from 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 and 24 equal pitches per octave) and Augusto Novaro, the Mexican microtonal theorist who composed studies in 15 equal, among others. Barbara Benary also formed Gamelan Son of Lion around this period, and Lou Harrison was instrumental in creating American gamelan orchestras at Mills College. In Europe, the "Spectralists" in Paris created their first works from 1973 on with an extensive use of microtonal harmony. The main composers were Hugues Dufourt, Gérard Grisey, Tristan Murail and Michael Levinas; see also the parisian ensemble "L'itinéraire". György Ligeti in Hamburg strongly promoted microtonality and used it in several of his works.
Digital synthesizers from the Yamaha TX81Z (1987) on and inexpensive software synthesizers have contributed to the ease and popularity of exploring microtonal music.
Elliott Sharp's groups Carbon, Tectonics and Terraplen make extensive use of just intonation microtonality to intensely dissonant and vibrant effect. Los Angeles guitarist Rod Poole has produced a number of rock-oriented xenharmonic CDs.
The band Crash Worship made use of Ivor Darreg's megalyra subcontrabass microtonal instrument for both xenharmonic and industrial noise purposes.
Elaine Walker of Zia has released several albums making use of the Bohlen-Pierce scale and other equal temperaments such as the 19tet and 10tet. Zia performs on electronic instruments that specifically do not reference the standard 12 tone tuning.
Jonny Greenwood, of the alternative rock band Radiohead, has experimented with microtonal music in both his solo material and his work with the band; for instance, the song Climbing Up the Walls, from the band's 1997 album OK Computer, includes a recording of sixteen violins playing quarter tones apart from each other to create a droning, atonal 'white noise' effect.
Other rock artists using microtonality in their work include Glenn Branca (who has created a number of symphonic works for ensembles of microtonally tuned electric guitars) and Jon and Brad Catler (who play microtonal electric guitar and electric bass guitar).
Microtonality often appears to occur in popular rock music in contexts where it is not notated or explicitly described as microtonal, but is nonetheless quite audible. Examples include the guitar introduction to the The Doors' song "The End", the extremely microtonal vocal line in Sinéad O'Connor's songs -- most notably on "Nothing Compares 2 U," -- and in the microtonal bass lines in songs like Siouxsie and the Banshees' "Israel." The November 2004 WSES Official Newsletter for Acoustics, Science, and Technology of Music mentions that "bands from Sonic Youth to Art Rock Circus have written music with non-standard and microtonal guitar tunings."
Explicitly microtonal jazz has also made a niche for itself as, for example, in the playing of trumpeter Don Ellis, who used a quartertone trumpet built to his specifications, woodwind player Joe Maneri, who has mapped what he calls the "virtual pitch continuum" onto the intervals of 72-tone equal temperament, and in albums released by percussionist Emil Richards, Lothar and the Hand People, the xenharmonic intonational inflexions of John Coltrane, and many others.