He was also secretary of the Music Section of the Academy of Arts from 1972 to 1974 and vice-president of the Association of Composers and Musicologists of the GDR [de] from 1977 to 1982.
After passing the examination, he waived the Abitur and began studying music in the main subjects composition with Konrad Friedrich Noetel [de] (student of Paul Hindemith) and Hermann Wunsch (student of Franz Schreker) and piano with Maria Petersen.
As a student, he set Bertolt Brecht's poem Legend of the Creation of the Book of Taoteking on the Way of Lao-tzu to Emigration [de] to music.
1 (1952), which received extraordinary praise from musicologists such as Georg Knepler and Eberhard Rebling as well as the Soviet composer Anatoly Novikov.
[16] After the suppression of the Hungarian Revolution of 1956 and the lessons learned from the 20th Congress of the Communist Party of the Soviet Union, he briefly thought of leaving the GDR for the West, but was then changed his mind by cultural officials Georg Knepler and Nathan Notowicz.
[18] In 1961, he was proposed by the Department of Culture of the Central Committee of the SED for admission to the Music Section of the German Academy of the Arts, but this was prevented by the composer Paul Dessau.
[19][20] In the same year Kochan undertook a study trip to Cuba and in 1962 became a member of the Friendship Committee GDR-Japan of the World Festival of Youth and Students.
[22][23] On his cultural-political ambitions Kochan later said:[24] "Despite all the difficulties, I always went my way, not out of egotistical intentions to succeed, but to make my specific contribution as a composer, comrade and citizen."
[15] In 1973, he received a full professorship in Berlin through the support of Ernst Hermann Meyer, who considered him "the most gifted composer of the middle and younger generations.
"[30] He was also a frequent lecturer at the Gera Summer Courses for Contemporary Music, founded in 1974[31] Among his best-known students today were the composers Udo Zimmermann, Lothar Voigtländer and Friedrich Schenker.
[15] After his first two symphonies and several vocal works, he ventured into opera Karin Lenz [de] in 1971, the premiere of which was realised under the conductor Heinz Fricke and the director Erhard Fischer at the Staatsoper Unter den Linden in Berlin.
[39] In the opening words it was stated: The composers' association has reacted [...] late, hesitantly and tactfully to socio-political challenges in recent years.
[44] Part of his estate is now in the Archive for Contemporary Composers of the Sächsische Landesbibliothek – Staats- und Universitätsbibliothek Dresden.
[53] Die Zeit-feuilletonist Heinz Josef Herbort especially counted his solo concertos as well as his symphonies [...] among the best that the GDR Republic could represent outside[54] The Ashes of Birkenau, in turn, is among the first East German compositions to deal with the Holocaust.
[55] Some of his chamber music works were written for renowned performers such as the Gewandhaus Quartet, pianist Dieter Zechlin and recorder player Markus Zahnhausen.
However, Kochan soon developed a quite independent style, which initially emanated from his models Paul Hindemith and Béla Bartók.
[56] Not Boulez, Messiaen or Varèse were musically appreciated by Kochan, but the moderate Polish composer Witold Lutosławski, who also received much attention in the GDR.
[61] The Dresden musicologist Dieter Härtwig described Kochan's works as having a "tendency to playful detachment, to cheerfulness and optimism.
[65] He achieved his mature style with compositions such as the cantata Die Asche von Birkenau (1965) based on a text by Stephan Hermlin, which has Auschwitz as its theme, and the 2nd Symphony (1968).
[32] He could no longer make friends with the consistent departure from tonal reference patterns and neoclassical tendencies of his student Friedrich Schenker.
The cultural journalist Erik Buchheister attributed Kochan's music an "appellative character" with humanist traits of a Karl Amadeus Hartmann.