[1] In 1951, Goeyvaerts attended the famous Darmstadt New Music Summer School where he met Karlheinz Stockhausen, who was five years his junior.
They found themselves deep in conversation, and performed a movement from Goeyvaerts's "Nummer 1", Sonata for Two Pianos, in the composition course by Theodor Adorno there.
[citation needed] Goeyvaerts became excited in 1952 when he learned that Stockhausen had access in Paris to a generator of sine waves.
At the time, Stockhausen did not share his enthusiasm, owing partly to the inability with the equipment at hand to superimpose sine tones.
Only later, after taking up his new post at the NWDR Electronic Music Studio in Cologne, did Stockhausen find more suitable equipment, in July 1953.