Musik im Raum - ZKM

How to Control 840 Channels.
Working with Large Scale Wave Field Synthesis
Marije Baalman
Technische Universität Berlin
1 Introduction
Wave Field Synthesis (WFS) is a method for
sound spatialisation. Its main advantage is
that it has no sweet spot, but instead a large
listening area, making the technology
attractive for concert situations. The main
principle of WFS is illustrated in figure 1.
A wave field can be synthesized by a superposition
of wave fields caused by a lot
of small secondary sources, provided you
calculate the right delays and amplitude
factors for the source signal for each secondary
source.
fig. 1: From the Huygens Principle to Wave Field Synthesis
2 WFS system in H0104
In 2006, the TU Berlin launched a project to equip one of the lecture halls (fig. 2) with a large
WFS system 1 of in total 840 loudspeaker channels, both for sound reinforcement during the regular
lectures, as well as to have a large scale WFS system for both scientific and artistic research
purposes. The lecture hall has seats for ca. 700 people, and a total wall length of ca. 100 m. The
loudspeakers are built into loudspeaker panels (fig. 3) 2 , each providing 8 audio channels, which are
fed with an ADAT signal. Each panel additionally has 2 larger speakers which emit the low-pass
filtered (< 200Hz) sum of the 4 channels above it. The speaker distance is 10 cm. Each channel is
Marije Baalman „How to Control 840 Channels“
fig. 2: The lecture hall H0104 of the TU Berlin with 840 channel Wave Field Synthesis system, Photo: Folkmar Hein
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