Kurzwellen, Nr. 25

Kurzwellen is one of a series of works dating from the 1960s which Stockhausen designated as "process" compositions. These works in effect separate the "form" from the "content" by presenting the performers with a series of transformation signs which are to be applied to material that may vary considerably from one performance to the next. In Kurzwellen and three subsequent works (Spiral for a soloist, Pole for two, and Expo for three), this material is to be drawn spontaneously during the performance from short-wave radio broadcasts (Kohl 1981, 192–93). While this separate treatment of the genetic rules for development had existed in Stockhausen's earlier compositions, the emphasis on the process of transformation and less specificity of what is to be transformed is taken further than ever before in Kurzwellen (Stockhausen 1989, 114). The overall formal process is therefore fixed, whereas the sound materials are extremely variable (Frisius 2008, 224). The processes, indicated primarily by plus, minus, and equal signs, constitute the composition and, despite the unpredictability of the materials, these processes can be heard from one performance to another as being "the same" (Kohl 2010, 137). While the use of radios in concert works dates back at least to 1942 with John Cage's Credo in Us, and Stockhausen may well have gotten the idea of using radios from Cage, their approaches could not have been more different. For Cage, the type of radio is a matter of indifference, since their purpose is merely to fill in prescribed time units with any sort of sound at all. Stockhausen, on the other hand, prescribed short-wave receivers because of their capability of bringing in broadcasts from far away, and for the rich variety of available sounds. These sounds are also not used indiscriminately: the performers are to search for and select only materials suitable for improvisational transformations (Kohl 2010, 135–37).