Karlheinz Stockhausen’s SPIRAL, a milestone in his oeuvre from 1968, was created in the context of his electroacoustic experiments and his commitment to instrumental virtuosity. SPIRAL achieved particular historical significance through its performances during EXPO 70 in Osaka, where it was presented daily to an international audience in the spherical auditorium of the German Pavilion, which Stockhausen co-designed.

The work is based on the interaction between a soloist and real-time signals captured via shortwave receivers. These signals, originating from global radio communications, serve as the starting point for an improvisational exploration in which they are imitated, transformed, and ultimately transcended. The performance requires a symbiotic relationship between musician, instrument, and ad-lib electronics, as the sonic events are unpredictable and demand a high degree of flexibility and sensitivity from the performer.

The shutdown of traditional shortwave broadcasts, as in Germany in July 2014, has made the faithful performance of SPIRAL considerably more difficult. To ensure the work remains accessible, I utilize the capabilities of Web-SDR (Software Defined Radio), a platform that enables the reception of global radio stations via the internet. In addition, I developed a special loudspeaker element: a sound sculpture consisting of a bumper ball and structure-borne sound drivers that makes satellite communication aurally and physically tangible. This miniature spherical auditorium translates the spatial and sonic aesthetics of SPIRAL into a contemporary format.

Stockhausen’s SPIRAL remains not only a masterpiece of electroacoustic music, but also an artistic reflection on the mechanisms of media perception. In an era characterized by the flood of digital information, the work offers a unique perspective on dealing with communication, transformation, and contextualization—topics that are more relevant today than ever before.