Tokyo Circle
interactive sound installation
(«Sound Art – Sound as Media», ICC InterCommunication Center, Tokyo, Japan; INM-Institut für Neue Medien, Frankfurt, Germany; «Hörgänge», Hermannshof Völksen, Germany; Galerie t-u-b-e, Munich, Germany; «Erlanger Hörkunstfestival», Markgraphentheater, Erlangen, Germany; «b!as Sound Art Exhibition», Taipei Fine Arts Museum, Taiwan)

Tokyo Circle allows for modulating a potential acoustic energy field—a virtual acoustic space—inside (or virtually overlapping) the exhibition room. The sound relates to the symbolic meanings of the circle.
The symbol of the circle has been used in ideographic writings in most cultures for several thousands of years and is a very powerful symbol, which can signify many different things. The dot, or filled circle for example denote something important, puts focus onto it. The filled and the empty circle, and especially the circle with an additional dot in the middle are symbols for the sun, or a center, the first two less often for the moon, also for spirit in a creative sense, as opposed to matter (in astrology), and all possibilities. All these meanings have in common a notion of energy.
The special power of the circle lies in its quality of unity and isolation (isolating the inside from the outside). The space that is enclosed by the circle constitutes an own powerful sphere, a sphere of enhanced meaning, in which mythical/magical and also creative actions are performed. In western magic, by encircling something one gains power over it, one can also ban somebody or something inside a drawn circle. Between the encircled and the encircler there is always a magical connection.

Technical Description
Tokyo Circle is an interactive audio installation based on a changing virtual acoustic space that responds to the movements of the spectator.
It is basically meant to be performed by one person at a time, as the connections between sound and movement are best perceived for a single performer.
Tokyo Circle consists of an elevated disk on three pods, on which the performer has to step on, a six-channel speaker system, a sensoric system that interpolates the performer’s position by a three-point mass measurement, and a device that maps sound events to invisible sectors inside the circle.
The sensors inside the pods continuously measure the weight on each of them and transform their measurements into electronic signals; a computer program calculates the performer’s position from the three signal streams. This means that the sound will only be active when a performer enters the installation and only as long as he stays inside it, because only then will there be a mass difference to the original mass of the disk.
The sounds of the virtual acoustic space are mapped to certain positions (sectors) inside the circle, and are triggered once the performer enters their positions. Another computer program controls the sample play setup for the sounds on the speaker system.

Photo credits:
top: Kwanho Yuh-Zwingmann, Völksen 2000
second from top: ICC–interCommunication Center, Tokyo 2000
bottom right: Volkmar Hoppe 1991