From childhood until his public debut in 1962 his mother has been his piano teacher. He studied music theory and composition
with Björn Fongaard and Finn Mortensen. He visited the Internationale Ferienkurse in Darmstadt and attended a composition
course in Stockholm.
Until 1961 he was mainly occupied with jazz, both as a pianist and as a composer and arranger.
On his music
Janson composes for both large and small ensembles, often integrating vocal elements.His early works show an interest in
European avant-gardism, but many of his more recent works integrate many influences such as late romanticism, jazz and
Norwegian folk music.
His music is often classified as neoexpressionism, making sonority a central element in many of his compositions, as,
frequently is a political theme.
1961 - Patrice Lumumba, piano, bass and drums
1962 - November 62, piano
1963 - Vuggesang (Lullaby), soprano and 48 strings
1965 - Canon, chamber orchestra and prerecorded tape
1966 - Konstruksjon og Hymne (Construction and hymn), orchestra
1967 - Theme, choir, reciter, piano, electronic organ and 2 percussionists
1967 - Nocturne, choir, 2 cellos, harp and 2 percussionists
1969 - Mot Solen (Towards the Sun), ballet
1970 - Valse Triste, voice, jazz quartet and tape
1972 - Music for the television series Alberte
1973 - Et Fjelleventyr (A Mountain Adventure), opera
1975-80 - Three Poems by Ebba Lindqvist
1976 - Forspill (Prelude), violin and orchestra
1977 - Vi som är födda vid havet, choir
1977 - Hymne til Josef
1978 - String quartet
1983 - Wings, mixed chorus and jazz-ensemble
1983 - Errotikk and Pollitikk, suite for mixed choir and organ with rhythm-box
1985 - Mellomspill (Interlude), orchestra
1988 - Nasjonalsang (National Song), solo trumpet, solo trombone, orchestra and tape