Unsichtbare Chöre

Unsichtbare Chöre (Invisible Choirs) is an eight-channel electronic-music composition by Karlheinz Stockhausen. A component part of the opera Donnerstag aus Licht (1977-80), it may also be performed as an independent composition, in which form it is designated "ex 49" in the composer's catalog of works (where Nr. 49 is Michaels Jugend, act 1 of the opera).