This device is commonly used to extend what would normally be a regular phrase into an irregular and extended phrase. Such expansion by interpolation is achieved by the addition of extra music in the middle of a phrase (commonly through the use of sequence).
Formerly, in the sung portions of the Mass, such as the introitorkyrie, it was permissible, especially during the medieval period, to amplify a liturgical formula by interpolating a "farse" (from Medieval Latin farsa, forcemeat),[2][clarification needed] also called "trope".[3] This might consist of an explanatory phrase or verse, usually in the form of an addition or paraphrase, often in the vernacular.
Interpolation (also known as replayed), especially in 20th-century music and later, is an abrupt change of musical elements, with the (almost immediate) resumption of the main themeoridea.[4] Pieces that are cited as featuring interpolation, among other techniques, are Music for Brass QuintetbyGunther Schuller and Threnody to the Victims of HiroshimabyKrzysztof Penderecki (both 1960–61).[4]
^William E. Caplin, Classical Form: A Theory of Formal Functions for the Instrumental Music of Haydn, Mozart, and Beethoven, p. 255. ISBN0-19-514399-X.
