In music theory, prolongation is the process in tonal music through which a pitch, interval, or consonant triad is considered 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. The English term usually translates Schenker's Auskomponierung (better translated as "composing out" or "elaboration"). According to Fred Lerdahl, "The term 'prolongation' [...] usually means 'composing out' (Schenker's own intention for the term is open to debate)."