Luc Döbereiner

Glas (2014)
site-specific piece for live-electronics

This work exists in two versions: a live-electronic version (Glas), which was first shown in April 2014 in the Brandenburgischer Kunstverein Potsdam, and an installation version (Reflexion), which was commissioned by the electronic music studio of the Technical University of Berlin and presented during the Electroacoustic Music Studies Network Conference 2014. As in Interior/Exterior, digital sound synthesis is connected to a physical set-up; that is, the method of sound production includes an algorithmic part and a physical material, which are interlinked. The work is based on a very specific sonorous spatiality, that of solid objects; therefore, it explores solid objects as sonorous spaces. Using transducers (loudspeakers for structure-borne sound) and contact microphones, audio feedback is created within six glass windows, which thereby become oscillating membranes. The work takes a concrete space and a specific materiality as its starting point and includes the architecture and the space in the construction of an instrument. The first version, Glas, was developed for a glass pavilion on the Freundschaftsinsel in Potsdam. The listening space and the pavilion itself were transformed into an instrument. The set-up also projected the sound outwards, thereby creating a sonorous redoubling of the architectural idea of translucency, which is essential for a glass pavilion.

In contrast to Interior/Exterior, the central sound generating method is not based on a physical model but on a feedback sine-wave oscillator the phase input of which is controlled by the signal coming from the contact microphones attached to the windows and whose output is again played back over the windows, which thus act as non-linear filters within the feedback process. Despite its simple design it can create complex, turbulent situations, periodic patterns, and noise. The system transforms the input signals again before feeding them back into the glass membranes using a variety of digital feedback processes, mainly in order to create a long-term memory and control-level feedback leading to more complex and interdependent behaviour from the six windows. The feedback network creates a non-linear space, which contains chaotic, periodic, and turbulent regions. This leads to an entanglement of spaces of different types: the phase space of the digital sound processing (its possible states), the exhibition or performance space, the solid space of the glass windows, and the acoustic space mediated by air. An essential aspect, which is also important for the other works presented here, is the idea that loudspeakers are not simply neutral means of reproduction but are themselves part of the sound production.

Moreover, there is a room microphone whose signal is analysed and used to steer all six independent processes in particular directions - that is, away from their current states. In the installation version, the system analyses its own input and always attempts to amplify inexistent or weak frequencies, leading to a continuous flux of situations. In the live-electronic version, Glas, I control the whole system in real time. There is a series of spaces of possibility, which I explore improvisationally.

19/04/2013, BKV Potsdam. Ausstellungspavillon auf der Freundschaftsinsel