(Fr. quart de ton; Ger. Viertelton; It. quarto di tono).
An interval half the size of a semitone. The term was used by some 17th- and 18th-century theorists to denote the distance between a sharp and enharmonically distinct flat in mean-tone temperaments (e.g. D–E). In most contexts, however, it refers to an interval of 1/24 of an octave, or 50 cents.
Quarter-tones form part of the enharmonic genus of ancient Greek music theory (see Greece, §I, and Diesis (ii)); they have also been discussed in the context of medieval plainsong (see Gmelch), and were considered by Hothby in the late 15th century (see Reaney) and by Coprario in the early 17th (see Field). Interest in them increased steadily during the 19th and 20th centuries. The ‘Aphorismen’ of Heinrich Richter, published in 1823 under the pseudonym ‘Amadeus Autodidactos’, ventured to propogate quarter-tone music, and Johanna Kinkel urged the emancipation of the interval in her essay of 1853. The Russian futurist painter Mikhail Matyushin (1861–1934) experimented with quarter-tones and wrote a related treatise; Julián Carrillo wrote quarter-tone music in the 1890s; and Andrzej Milaszewski (1861–1940) patented a quarter-tone piano in Vienna in 1912. The Czech composer Alois Hába taught courses on quarter-tone (and sixth-tone) music at the Prague Conservatory from 1924 to 1951. Bartók used quarter-tones in the last movement of the original version of his Sonata for solo violin (1944; see Nordwall). Other composers who have written quarter-tone music include Ivan Vïshnegradsky, Valentino Bucchi and Charles Ives, as well as Boulez and many other composers of the second half of the 20th century.
The theory and practice of quarter-tones are at least as widespread beyond western Europe as within it. The early 10th-century Islamic theorist al-Fārābī described the ostensible use of approximate quarter-tones in the fretting of a long-necked lute, tunbūr baghdādi, which he deemed pre-Islamic, and quarter-tones have remained a feature of much Arab music. The concept of quarter-tones was a prominent feature in the analysis of scales by 19th- and 20th-century Islamic theorists, most notably Mikhā'īl Mushāqa (1800–88). Many Hindu theorists have considered the octave to de divided into 22 sruti which, though seldom regarded as uniform in size, must average about 55 cents (see India, §III, 1(ii)(a)).
See also Microtone and Microtonal instrument; Tetrachord.
F. Busoni: Entwurf einer neuen Ästhetik der Tonkunst (Trieste, 1907, 2/1910/R; Eng. trans., 1911/R)
J. Gmelch: Der Viertelstonstufen im Messtonale von Montpellier (Eichstatt, 1910)
H.G. Farmer: ‘Musikiya’, The Encyclopaedia of Islam (Leiden, 1913–38, 2/1960)
L. Kallenbach-Greller: ‘Die historischen Grundlagen der Vierteltöne’, AMw, viii (1926), 473–85
L. Sabaneyev: ‘The Possibility of Quarter-Tone and Other New Scales’, MT, lxx (1929), 501–4
A. Holde: ‘Is there a Future for Quarter-Tone Music?’, MQ, xxiv (1938), 528–33
O. Nordwall: ‘The Original Version of Bartok’s Sonata for Solo Violin’, Tempo, no.74 (1965), pp.2–4
C.D. Field: ‘Music Observations from Barbados, 1647–50’, MT, cxv (1974), 565–7
E. Weissweiler, ed.: J. Kinkel: ‘Friedrich Chopin als Komponist’, Dissonanz, viii (1986), 7–11
G. Reaney: ‘The Musical Theory of John Hothby’, RBM, xlii (1988), 119–33
S.L. Marcus: Arab Music Theory in the Modern Period (diss., UCLA, 1989)
I. Nest'ev: ‘Iz istorii russkogo muzykal'nogo avangarda: Mikhail Matyushin, Pobeda nad solncem’ [From the history of the Russian musical avant garde], SovM (1991), no.3, pp.66–73
P. Cahn: ‘Amadeus Autodidactos und seine Aphorismen über Musik (1823)’, Musiktheorie, ix (1994), 85–91
JULIAN RUSHTON