 Electronic, electroacoustic, and computer music, pioneered in the 20th century, continue to develop in the 21st century.One of the major figures in the early development of electronic music, Karlheinz Stockhausen, composed his last electronic works—"" and eight further pieces derived from it—as hours 13 to 21 of his "Klang" cycle (2005–2007).Mario Davidovsky has extended his series "Synchronisms", which in live performance incorporate both acoustic instruments and electroacoustic sounds played from a tape.