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localized sound where each user has his or her own speaker, and (2) coded
sound where users share one speaker but the waveform of the sounds are
varied so that a different sound is played for each user. This could be one
practical solution to business-oriented applications, but is not sufficient for
sound-centric applications (e.g., computer music).
An experiment by Ogi and colleagues using multichannel speakers like
ours was researched [15]. It is specially designed for a CAVE-like 3-D immer-
sive system and is rather complex and expensive. Even more important,
sound processing must be carried out beforehand for every possible position
of sound sources and the audience. Certain sound data is selected and then
presented to the user at the time of interaction with the system. Meanwhile,
in our trial, sound processing is executed on the fly.
Transition Soundings [16] and Orbophone [17] are specialized interfaces
using multiple speakers for interactive music making. A large number of
speakers are mounted in a wall-shaped board in Transition Soundings,
while Orbophone houses multiple speakers in a dodecahedral enclosure.
Both systems are deployed for sound art and their goal is different from
ours.
8.3 System overview
8.3.1 Organization of the System
The system we propose in this paper is designed to provide users with
effective visual and auditory feedback in performing collaborative work.
Figure 8.1 shows a physical setup of the system. The system is organized by
Sound Table as its central equipment, a pair of cameras, a video projector,
and a PC (not shown) [18].
Sound Table is a table in which 16 speakers are equipped in a 4 × 4 matrix,
as shown in Figure 8.2. It is of 90 cm width and depth, and 73 cm of height.
The distance between two adjacent speakers is 24 cm. Two 8-channel audio
interfaces (M-AUDIO FireWire 410) are equipped to the PC (Apple Mac Pro),
and connected to Sound Table through a 16-channel amplifier. The top of
Sound Table is covered by a white cloth so that computer-generated graphi-
cal images can be projected onto it. The video projector that is mounted over
Sound Table is provided for this purpose.
The user expresses his or her commands by manipulating a stick device
over Sound Table. Figure 8.3 shows the device whose base unit is Nintendo
Wii Remote [19]. The Wii Remote has unique and powerful capabilities as
a gesture controller, and many research trials of using it have been investi-
gated (e.g., for music composition [20]). We customized it by newly attach-
ing an infrared LED at its head. The position of the LED in a 3-D space
