He began with a general private music study with Wilhelm Siebler from 1942 until 1945, when he started piano lessons with Wilhelm Resch, and continued study with him until 1949 at the age of 19. He continued then with music history through 1952, under Eric Doflein (Attinello 2001). Simultaneously he began composition (in 1950) under several Musicians, including Ernst Krenek, Theodor W. Adorno, and Pierre Boulez. This led to his attendance at the University of Tübingen, where he studied musicology under Walter Gerstenberg, as well as theology and philosophy, while picking up further piano study as well. In 1955 however, the degree he left with was in fact theology, but with a dissertation about Arnold Schoenberg. Soon after, Camilla Riegger became his wife (in 1956), which led to a son and daughter. He became a minister, and taught theology and religion until 1963, when he added philosophy and psychology to his teaching practices. In 1968 his wife, Camilla, died, after which he underwent a period of psychoanalysis. In 1970 he remarried, to Iris von Kaschnitz, and began teaching religious studies and music in Munich, which he continued until 1976 (Attinello 2001). Then in Berlin, starting in 1970, he became a professor of experimental music and music research, with subsequent visits to the U.S. for other opportunities. Since 1976 he’s been teaching composition on and off in Berlin.
The Versuche (4 works, 1953–56) concern serial techniques of composition, exploring space by putting large gaps between performers. Being highly religion-oriented in background and in practice as he is, his contributions to the world of modern religious music were some of the more important works: Für Stimmen (...missa est) (4 works, 1956–69) is a set of vocal and organ experiments regarding prayers and verses of the Bible. Produktionsprozesse is a group of "language and body" compositions which concerns more of the physical act of sound producing itself rather than the actual sound being produced...with the performers utilizing speech and breathing organs (tongue, throat, etc.) in unusual styles through exercises which grow into a musical texture and atmosphere of broad communication formats.
His earliest works were strongly influenced by Karlheinz Stockhausen, about whose early works he wrote an extended essay; starting in 1959, he came under the influence of John Cage (Clements 1992).
Schnebel has had an important impact on the development of vocal music, and continues using both tonal and atonal approaches. Awards include the Arts Prize of Lahr in 1991. The first European Church Music Prize was conferred upon him in Schwäbisch Gmünd in the same year. He has been a member of the Berlin Akademie der Künste since 1991 and the Bayerische Akademie der Künste since 1996.
Invited by Walter Fink, he was the sixth Composer featured in the annual Komponistenporträt of the Rheingau Musik Festival in 1996.
Other stylistic choices of his fancy are influenced by Henry Cowell and his "elastic music", by raising and lowering predetermined melodic pitches, placing excess notes on top of them, rhythmic and tempi values distorted within voices, as well as dynamics. He also required multiple conductors with multiple choirs /ensembles when certain pieces were performed, although they were meant to stay out of synch with each other. John Cage and Mauricio Kagel were other prominent influences, and worked through Cage's unpredictability by setting up musical compositions that were followed, but not always set in stone, on the staff paper when performed. Additional concepts were explored through the art of theatrical music: i.e., the body language and "dance" of a Conductor during a performance, or say a solo Pianist and his audience would be performers together for one of his songs—visual elements were often involved. Works also include musical theatre.
Theories self-created and inherited were/are often practiced at performances. He believed that a student’s vocal range could be increased through the use of specific psychological methods, or physical placement. For Example, placing Singers far apart in a triangular shape causes a musically spatial feeling, and therefore sounds much different from the density when Singers are close together. Other times he may just take a traditional piece and turn it into an improvised 13-voice canon. Pieces using such theories can be found in his most famous works' set; the Fur Stimmen (...missa est) choral pieces, like :! (madrasha 2) and AMN. The first, an unpronounceable title, means "a non-verbal outburst or exclamation", and is used to explore the options in human phonetic sounds, such as vocal and musical versions in lips, tongue, glottus, nasal and other pressures through pitches. The second (unvocalized Hebrew) emphasizes the idea of musical space, with several large gaps in the piece, as well as bizarre vocal experiments.