The Haus der Musik presents itself as a contemporary sound museum. Here the phenomenon of music is presented as a multimedia experience. Visitors set out on virtual trips and discover new things by trying them out for themselves; they can wander through worlds of sound and even compose music themselves. The Haus der Musik has won many international awards and continues to be a magnet for the public. The team of checkpointmedia planned and developed numerous theme stations for visitors to experience, and implemented the appropriate technology. In addition, they planned and implemented the entire, high-grade audio/video and lighting technology of the multifunctional conference room on the top floor (light, sound, drapes, projector functions, etc.). The central installation of the Haus der Musik is the "Virtual Conductor", which enables visitors to conduct the Vienna Philharmonic Orchestra themselves. The conductor's baton is "tracked"; the computer recognises how fast the baton is being moved, how expansive or intensive these movements are; the corresponding instructions are then transmitted to the Philharmonic's film. The film was shot in many short sequences showing the real Vienna Philharmonic carrying out various activities and in different moods. The musicians can now "react" according to the conductor's skill and talent; visitors receive feedback in real time and directly experience the result of their conducting. If totally lacking in talent, they just have to live with the fact that the Vienna Philharmonic players are not amused and simply get up and leave. (Technical development of the exhibit by Prof. Max Mühlhäuser, Technische Universität Darmstadt and Prof. Jan Borchers, Rheinisch-Westfaelische Technische Hochschule Aachen). A "random control" device from the eighteenth century: Wolfgang Amadeus Mozart developed a musical module made up of numerous individual short melodies, which can be constantly recomposed into thousands of different variations by throwing dice. Theoretically there are 1,679,616 possible combinations when using his musical module. To transpose this musical game into the present day, two special tables were developed with sensor technology, which optically read out the result at the throw of a dice. The corresponding melodies are retrieved from a database and linked together. Projection and sound system enable visitors to experience in real time what they have "composed" according to Mozart's rules.