Karlheinz Stockhausen (1928-2007) was was a pioneer in the development electronic music and the first to introduce controlled chance into serial composition. He was one of the most innovative and influential composers of the second half of the 20th century and early 21st century, but also one of the most controversial.
Born near Cologne, Germany, Stockhausen's early life was deeply scarred by the horrors of Nazism and the resulting devastation of his country. He began his music education with piano lessons from age seven and later took up the oboe and violin. He went on study at the Hochschule für Musik Köln and the University of Cologne, and then with Olivier Messiaen in Paris and with Werner Meyer-Eppler at the University of Bonn.
Stockhausen was highly prolific, creating more than 300 works during his nearly 60 years of composing. Reflecting his wide range of interests, his works varied widely in style and media, and included orchestral works, full-length operas, instrumental solos, chamber music and choral works.
Among the best known of his works is the monumental Gruppen, which premiered in 1958. It was written for three full orchestras, each with its own conductor, and with a total of 109 players. It was inspired by shapes of the Graubünden Alps, which Stockhausen could see from his home. As with some other works of his, the lack of a unified beat or tonal center left the outcome of each performance to chance.
The Klavierstuck IX [Piano Pieces] is a series of compositions begun in 1952 with four short pieces for the piano and decades later expanded to a total of 21 works. The latter ones are written for synthesizers or other electronic instruments, which he came to view as the inevitable successor to the piano.
Stockhausen's last electronic work was Cosmic Pulses, which debuted in 2007. Central to this piece is the number 24, as it is constructed with 24 layers of sound, 24 different tempi, and 24 melodic loops, which are spaced throughout 24 different registers (spanning seven octaves).