Karlheinz Stockhausen (b.  1928) is one of the most important  and  controversial composers of the 20th century. He is best known for his ground-breaking work in electronic music and aleatory (controlled chance) in serial composition. He has written over 300 individual works.

Stockhausen studied music pedagogy and piano at the Cologne Musikhochschule, and musicology, philosophy, and Germanics at the University of Cologne (1947–51). It was only in 1950 that he developed a real interest in composition, and was admitted at the end of the year to the class of Frank Martin in Cologne. He continued his studies in Paris, early in 1952, and began attending Messiaen’s courses and Milhaud’s classes. In March 1953 he left Paris to take up a position as assistant to Herbert Eimert, at the newly established

Electronic Music Studio of NWDR in Cologne (in 1962 he succeeded Eimert as director of the studio). From 1954 to 1956 he studied phonetics, acoustics, and information theory at the University of Bonn. Together with Eimert, he edited the influential journal Die Reihe from 1955 to 1962.

After lecturing at the Internationale Ferienkurse für Neue Musik at Darmstadt (first in 1953), Stockhausen gave lectures and concerts in Europe, North America, and Asia. He was guest professor of composition at the University of Pennsylvania in 1965, and at the University of California, Davis, in 1966-67. He founded and directed the Cologne Courses for New Music from 1963 to 1968, and was appointed Professor of Composition at the National Conservatory of Music, Cologne, in 1971, where he taught until 1977. In 1998, he founded the Stockhausen Courses, held annually in Kürten (Germany).

Starting from just after his first Darmstadt visit in 1951, Stockhausen began working with a form of athematic serial composition that rejected the twelve-tone technique of Schoenberg. Compositions from this phase include Kreuzspiel (1951), the Klavierstücke I–IV (1952), and the first (unpublished) versions of Punkte and Kontra-Punkte (1952). Starting in 1953, he turned to electronic music, first producing two Electronic Studies (1953 and 1954), and then introducing spatial placements of sound sources with his noted work Gesang der Jünglinge (1955–56). His position as the leading German composer of his generation was established with this work and three concurrently composed pieces in different media: Zeitmaszefor five woodwinds, Gruppen(1955-7) for three orchestras, and Klavierstück XI (1956).

His work with electronic music and its utter fixity led him to explore modes of instrumental and vocal music in which performers’ individual capabilities and the circumstances of a particular performance may determine certain aspects of a composition. Examples of these procedures are found in Zyklus (1959), Klavierstück XI or Momente(1962-64/69). In 1960 Stockhausen wrote an important vocal piece, Carré for four choirs and four orchestras. He pioneered live electronics in Mixtur(1964/67/2003) for orchestra and electronics, Mikrophonie I (1964) for tam-tam, two microphones, two filters with potentiometers  (6  players),  Mikrophonie  II  (1965)  for  choir,  Hammond  organ,  and four ring modulators, and Solo for a melody instrument with feedback (1966). He also composed two electronic works for tape, Telemusik(1966) and Hymnen (1966-67). At this time, Stockhausen also began to incorporate pre-existent music from world traditions into his compositions: Telemusikwas the first overt example of this trend. Through the 1960s, Stockhausen explored the possibilities of “process composition” in works for live performance, such as Prozession(1967), Kurzwellen, and Spiral (both 1968), culminating in the verbally described “intuitive music” compositions of Aus den sieben Tagen (1968), Für kommende Zeiten (1968-70), and Ylem (1972). In 1968 Stockhausen composed the vocal sextet Stimmung, for the Collegium Vocale Köln, an hour-long work based entirely on the overtones of a low B-flat.

Beginning with Mantra(1970), Stockhausen turned to formula composition, a technique which involves the projection and multiplication of a single melody. He continued to use this technique through the completion of the opera-cycle Lichtin 2003. Some works from the 1970s did not employ formula technique, but nevertheless share its simpler, melodically oriented style (Conen 1991, 57). Two such pieces, Tierkreis(“Zodiac”, 1974–75) and In Freundschaft (“In Friendship”, 1977), have become Stockhausen’s most widely performed and recorded compositions. This dramatic simplification of style provided a model for a new generation of German composers.

Between 1977 and 2003 he composed a cycle of seven operas called Licht:Die sieben Tage der Woche (“Light: The Seven Days of the Week”). The Lichtcycle deals with the traits historically associated with each weekday (Monday = birth and fertility, Tuesday = conflict, Wednesday = reconciliation and cooperation, Thursday = learning, etc.), and with the relationships between and among three archetypal characters; Lucifer, Michael, and Eve. Stockhausen’s conception of opera is based significantly on ceremony and ritual, with influence from the Japanese Noh theatre, as well as Judeo-Christian and Vedic traditions.

Since completing Licht, Stockhausen has embarked on a new cycle of compositions, based on the hours of the day, titled Klang (“Sound”).