an expedition to new sound and light wave aesthetics The composers and media-artists Klaus Obermaier and Robert Spour have been working together with the German laser artist, Friedrich Foerster, for two years on the interactive interlinking of music and laser. The German computer specialist Kurt Walz developed a software for this project which, on the one hand, enabled the musicians to directly control the laser by their instruments, and on the other hand, made possible a completely new kind of sound control by deflecting the laser jet as a result of the musicians´ movements. For Immateriaux Obermaier/Spour created a new instrument: the 'plexi-drums', played live by drummer Wolfgang Reisinger. The music/laser project IMMATERIAUX received significant critical acclaim when it was performed at the ARS ELECTRONICA Festival 1992. Subsequent performances took place at the Vienna Concert House, the Festspielhaus Salzburg and abroad. As an interactive installation IMMATERIAUX was shown at galleries and museums in Europe and the USA, and led to the creation of Obermaier/Spour's first interactive CD-ROM.