Isorhythm (iso or same) consists of an order of durations or rhythms, talea ("cutting", plural taleae), which is repeated within a tenor melody whose pitch content or series, color (repetition), varied in the number of members from the talea. The term was coined in 1904 by Friedrich Ludwig to describe this practice in 14th and 15th century polyphonic motets but is also used in motets of the middle ages, the music of India, and by modern composers such as Alban Berg, Olivier Messiaen, and John Cage. It may be used in all voices or only a few voices. In motets, it began in the tenor voice but was then extended to higher ones. Friedrich Ludwig applied again in 1910, still for the 13th century, to successive phrases of qual length but not necessarily the same rhythm, a phenomenon whose 14th-century use Besseler called 'isoperiodic' (the German noun is Isoperiodik), meaning that 'the upper voices only follow the plan of the lower voices in a general way or have merely a few bars rhythmically identical in each Tenor period'. Isoperiodicy, unlike isorhythm, cannot survive diminution of the overall lenth of a phrase. Sanders developed the idea of modular numbers to represent the periodic construction of motet upper voices bounded by rests (Grove 6; 1973), sometimes non-coincident, or offset (Isorhythm. Bent, Margaret. Grove, 2nd ed. vol. 12 page 621). ISO has many meanings: Iso is the stem of the Latin transliteration of the Greek word ίσος (ísos, meaning equal). The iso- prefix in English derives from this and means equality or similarity. ... A duration is an amount of time or a particular time interval. ... Rhythm (Greek ρυθμός = tempo) is the variation of the duration of sounds or other events over time. ... In music, a tenor is a male singer with a high voice (although not as high as a countertenor). ... Look up melody in Wiktionary, the free dictionary. ... In music, pitch is the perception of the frequency of a note. ... Color is an important part of the visual arts. ... Repetition is the occurrence of an event which has occurred before. ... Polyphony is a musical texture consisting of several independent melodic voices, as opposed to music with just one voice (monophony) or music with one dominant melodic voice accompanied by chords (homophony). ... In Western music, motet is a word that is applied to a number of highly varied choral musical compositions. ... A musician plays the vielle in a 14th century medieval manuscript. ... The music of India includes multiple varieties of folk, popular, pop, and classical music. ... Alban Maria Johannes Berg (February 9, 1885 – December 24, 1935) was an Austrian composer. ... Olivier Messiaen (IPA: or ; December 10, 1908 – April 27, 1992) was a French composer, organist, and ornithologist. ... John Cage John Milton Cage (September 5, 1912 – August 12, 1992) was an American experimental music composer and writer. ... The word voice can be used to refer to: Sound: The human voice. ... In music, a tenor is a male singer with a high voice (although not as high as a countertenor). ...

The earliest Italian uses of rhythmic repetition are in motets but in madrigals: Landini's Si dolce non sono and Lorenzo da Firenze's Povero zappator, in which short units are immediately followed by their own diminutions and the resulting larger patterns are repeated. Only after 1400 did isorhythm enter the Italian tradition of cermonial and occasional motets (Bent, 1992; Allsen, 1992, chap. 3). In each half of Ciconia's motet Petrum Marcello the tenor follows the undiminished form immediately with its diminution, while in two other motets Ciconia makes the second half an undiminished rhythmic replication, in all voices, of the first(Isorhythm. Bent, Margaret. Grove, 2nd ed. vol. 12 page 621).

Ars nova composer Philippe de Vitry has been credited with the invention of the technique, but it "was neither an invention of Philippe de Vitry nor his exclusive property in the early fourteenth century." The isorhythmic construction was often varied through the use of strict or free rhythmic diminuation in the repetion of the color. (ibid, p.363) The ars nova was a stylistic period in music of the Late Middle Ages, centered in France, which encompassed the period from the publication of the Roman de Fauvel (1310 and 1314) until the death of Machaut (1377). ... Philippe de Vitry (October 31, 1291 – June 9, 1361) was a French composer, music theorist and poet. ...

The talea was often a rhythmic mode. The color of isorhythm may be compared with the tone row of the twelve-tone technique's fixed order of pitches and varied durations. In medieval music, the rhythmic modes were patterns of long and short durations (or rhythms) imposed on written notes which otherwise appeared to be identical. ... In music, a tone row or note row is a permutation, an arrangement or ordering, of the twelve notes of the chromatic scale. ... Twelve-tone technique (also dodecaphony) is a system of musical composition devised by Arnold Schoenberg. ...

Coloration also refers to otherwise perfect notes colored red or with an open notehead to indicate the loss of 1/3 their duration, making them imperfect.

Source

• Hoppin, Richard H. (1978). Medieval Music. New York: W.W. Norton & Co. ISBN 0393090906.

External links

• Here Of A Sunday Morning WBAI 99.5 FM: Isorhythm
• Isorhythm and Hocket in Guillaume de Machaut's Hoquetus David By Mark A. Zobel, Paper Presented at the University of Colorado Doctoral Research Seminar on Black-Note Mensural Notation, Boulder, Colo., April 1999
• London Sinfonietta's Isorhythm composition game