Prolongation

In music theory, prolongation is the process in tonal music through which a pitch, interval, or consonant triad is able to govern spans of music when not physically sounding. It is a central principle in the music-analytic methodology of Schenkerian analysis, conceived by Austrian theorist Heinrich Schenker.

Prolongation can be thought of as a way of generating musical content through the linear elaboration of simple and basic tonal structures with progressively increasing detail and sophistication. Important to the operation of prolongation is the hierarchical differentiation of pitches within a passage of tonal music. Typically, the note or harmony of highest hierarchical significance is the tonic, and this is said to be "prolonged" across durations of music that may feature many other different harmonies. (However, in principle any other type of consonant chord, pitch, or harmonic function can be prolonged within tonal music.) Conversely, in a chord progression, harmonies are said to prolong a triad when they are subordinated to that governing chord in a systematic manner; the job of such prolonging harmonies is to express and extend the influence of that hierarchically super-ordinate pitch or triad. Because it enables a pitch or pitches to remain in effect over the course of a piece, even as many other harmonic events intervene, prolongation is central to the concept of tonality in music.

The early 20th-century music theorist Heinrich Schenker (1868–1935) was responsible for developing both the conceptual framework for prolongation and a means of analyzing music in terms of prolonged musical structures (called Schenkerian analysis).

Schenker’s own usage of the term differs from the modern one. The German word Prolongation is not common, and Schenker first used it in a very specific meaning (maybe originating in legal, possibly Viennese vocabulary), referring to the extension of the primal laws (Urgesetze) or of the primal concepts (Urbegriffe) of strict composition in free composition and the phenomena resulting from the extension of these laws. He used the word mainly to denote the transformation of a given level of voice-leading to the next one, describing the passage from level to level as a Prolongation. Adele T. Katz appears to be responsible for the shift of meaning where "prolongation" became the American translation of Auskomponierung, "elaboration".

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