The son of a Jewish-German father and English mother, Halbreich studied with Arthur Honegger and later with Olivier Messiaen at the Paris Conservatoire, gaining a first prize in analysis and history of music.[3] He later made his base in Belgium. From 1970 to 1976 he was Lecturer (German: Dozent) in Musical Analysis at the Royal Conservatory in Mons. He worked on numerous radio broadcasts and co-founded the Belgian music magazine Crescendo for which he was a major contributor.[1] From 1973 to 1976 he was artistic director of the Festival de Royan.[3]
He was known for a number of books, articles and studies on modern and contemporary music, including monograph works on Olivier Messiaen, Claude Debussy, Arthur Honegger, and Bohuslav Martinů. He prepared musical catalogues of the works of Honegger and Martinů, and their works are therefore sometimes referred to by their H number. He assisted Nicolas Bacri in orchestrating Honegger's opera, La morte de Sainte Alméenne, originally written in 1918 for voice and piano; the new version was premiered in Utrecht on 26 November 2005, on the 50th anniversary of the composer's death.
He had a broad interest in culture, and while a convert to Catholicism, he was open to, and expressed deep knowledge of eastern spiritual history alongside Christian mystics.[3]
He died on 27 June 2016 at the age of 85.[4]
Of his three children, the eldest Frédéric is a painter.[3]
Musiciens d'Europe, together with Paul-Gilbert Langevin, La Revue Musicale, N°388/390, 1986. (ISSN0768-1593)
Roumanie, Terre du Neuvième Ciel, together with Ana Maria Avram, interviews and papers, Bucharest, Edition Axis Mundi, 1992 (215 pages).
La Musique Spectrale au début du XXIè Siècle, conference in Paris with Harry Halbreich, Ben Watson, Costin Cazaban, Sébastien Beranger, moderated by Ana Maria Avram, CREMAC, 2006 (234 pages).