Isorhythmic tenor from the first part of the
Kyrie of
Machaut's
Messe de Nostre Dame (c. 1360). A
color of 28 notes is arranged with a four-note
talea pattern which repeats seven times.
Isorhythm (from the Greek for "the same rhythm") is a musical technique that arranges a fixed pattern of pitches with a repeating rhythmic pattern.
Detail
It consists of an order of durations or rhythms, called a talea ("cutting", plural taleae), which is repeated within a tenor melody whose pitch content or series, called the 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.
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 diminution in the repetition of the color. (Hoppin 1978, p.363)
The talea in early isorhythmic compositions was usually a short sequence of only a few notes, often corresponding to a rhythmic mode. In the course of the 14th century, taleae became much longer and more elaborate, and were used to structure much more large-scale works, where each color and talea constituted a substantial structural section of a composition measuring many bars. Around 1400, the technique of the diminution motet became common: a long tenor color was repeated several times according to different mensuration rules, making its performance faster by a fixed proportion each time. This technique was still used in the large-scale ceremonial motets by Guillaume Dufay in the mid-15th century, but his work also marks the extensive use of the more fluid polyphonic styles of the early renaissance. Dufay's motet Nuper rosarum flores, written for the inauguration of the new dome of Florence Cathedral in 1436, is regarded as the last great isorhythmic motet composition.
In modern usage, the term "isorhythm" is often associated with the practice of repeating two sets of parameters (such as duration and pitch) at different rates so that the values of one parameter are associated with different values of the other parameter at each repetition. The color of isorhythm may be compared with the tone row of the twelve-tone technique's fixed order of pitches and varied durations. The modern musical innovation of integral serialism sprang from a study of the 12 tone compositions of Anton Webern and the isothythmic organization within motets of Guillaume de Machaut.
The Isorhythmic Motet
These motets, written during the Ars Nova period of the 1300s, feature the isorhythmic principles of talea and color. Composers include Machaut and Philippe de Vitry. An example of an isorhythmic motet is Garrit Gallus/In nova fert/Neuma, composed by Philippe de Vitry in the early to mid 1300s.
Structural plan of the tenor of a late medieval isorhythmic motet with threefold diminution,
Sub Arturo plebs by
Johannes Alanus. There is a color of 24
longae (48 bars in modern notation), divided in three
taleae. The
color is repeated three times, each in a different mensuration. Its length is subsequently diminished by the factors of 9:6:4. The graphic shows (a) the preexisting
Gregorian cantus firmus; (b) the tenor as written in
mensural notation; and (c) a partial transcription of the beginnings of each of the nine
taleae in modern notation.
Sources
- Hoppin, Richard H. (1978). Medieval Music. New York: W.W. Norton & Co. ISBN 0-393-09090-6.
External links
_isorhythmic_tenor.svg)
