Previous Work
Compression grew out of a series of sound installations and compositions that in various ways investigate space and audio feedback. The focus in these works is on different forms of interior spaces, such as sound within solid bodies (metal sheets and glass) or within the interior of an acoustic instrument. A principle intention was to employ digital sound synthesis methods not merely as sources for sounds with a particular character or to explore some abstract behaviour but to connect the sound generating methods in their inner workings with the form and particular site of the work’s presentation. The intention was to blur the border between ‘formal’ sound synthesis and ‘empirical’ sound reproduction, between an abstract method and a concrete site, space, physical instrument, or listening situation. Agostino Di Scipio’s installation works and some of his compositions for wind instruments have been important reference points for these works. In particular the use of the saxophone in Modes of Interference 21 has influenced my work Innenraum, which uses a somewhat similar set-up for the same instrument.
The relation between sound and its description is essential in these works. I have tried to avoid thinking about and composing sound in terms of representation, but rather as the result of processes, actions, performances, and operations. Even if structural situations are described by sets of parameter values or musical notations there is no actual mapping in a representational sense, at least no one-to-one mapping, since due to the state of the set-up, system, or acoustic space the description of a situation does not correspond unequivocally to a sonorous situation. It is thus rather the description of a transformation: an operation but not a representation.
The works presented here deal with several entangled types of materiality (of sound). There are physical set-ups and spaces, there are synthesis processes in which sound inscribes itself as a digital signal, there is the materiality of the signifier in terms of notations and programs, and there is the modelling of physical processes, which I did not think of as a simulation, but rather used because of its behavioural characteristics, dynamics, and complexity.
Technology reflects political and social power and attitudes towards the control of the material world. The works presented here share an understanding of technology as providing access to the materiality of sound and not as a means of impressing, overwhelming, or overpowering, or as a means of creating a functional realisation of a preconceived ideal. I generally try to use open, cheap, and easily accessible technology as a practical tool of investigation and thought. I try to understand technology as a way of connecting thought and material, as a way of materialising thought and letting concepts and ideas be ‘touched’ by material realities.
Interior/Exterior was presented at the exhibition space ESC in Graz, Austria, in January 2012. The installation consists of, on the one hand, a physical set-up consisting of a metal sheet (a roof tile), six loudspeakers, and four microphones, and, on the other hand, a physical modelling sound synthesis program. The metal sheet resonates, it responds non-linearly and differently depending on the location of the excitation – that is, the placement of the loudspeakers. There are six loudspeakers facing upwards under the plate and four loudspeakers (used as microphones) facing downwards on top of the plate (see image). The sound output hence excites a body at different places, while the loudspeakers scan its resonances and feed the resulting signal back into the software synthesis model. The metal sheet thus acts as a vibrating speaker membrane, projecting the sound upwards.
The synthesis method itself is based on the idea of a circle of connected springs and masses that are being displaced by input signals (recorded by the microphones) and stochastic processes2. The circular structure is thus set in motion and vibrates according to the physical properties of the springs and masses. The resulting dynamic motion is being scanned; that is, the positions of the masses are read and used to construct an audible waveform. The synthesis model combines aspects of Iannis Xenakis’s Dynamic Stochastic Synthesis3 and Scanned Synthesis4. It creates sounds with complex transients whose characteristics can be changed by altering the physical properties of the system, it creates a continuum between periodic and noisy sounds, and it can be used to process input sound.
In a similar way, the metal sheet acts as a vibrating object that is excited and scanned (recorded). The recorded signal is fed into the synthesis model whose output is subsequently used to excite the metal plate again. This feedback loop between synthesis model and physical model creates an entangled symmetry of excitation and scanning. The synthesis model thereby extends into a physical set-up that blurs the border between abstract model and concrete reproduction. Neither part can exist (i.e., sound) without the other, nor can the separation of empirical reality and formal model be clearly made. The model becomes something like a ‘participation’: an intersection of sonorous materiality and formal procedures.
Not everything, however, is determined by the set-up and the synthesis process or by a behavioural pattern dependent on input data. Instead of having organic connections between all parts of the system, there is also a scission in its structure and some decisions are not based on the input or the state of the system. These decisions control the generation of the formal temporal development of the installation. There are six independent voices, which are the result of six ways of scanning the same physical model. They form six perspectives on one object – six different paths by which to scan the object’s motions. The voices initially proceed from a common starting point. They then diverge, each voice’s parameters undergoing independent trajectories until only one voice remains, which forms the next starting point. There is thus an oscillation between moments of strong cohesion and moments of divergence. The durations of the trajectories are very varied; the process may thus give rise to short gestures as well as long textural transitions.
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.
Innenraum is a work for alto saxophone, piano, percussion (one udu and one tam-tam), and live electronics that was commissioned by the Swiss ensemble Werktag and premiered in June 2015.
The composition deals with the idea of treating the instruments primarily as acoustic spaces, which are variably connected to one another by means of the live electronics. Each instrument contains both a microphone and a loudspeaker or transducer: A small electret microphone is placed in the neck of the saxophone and a small loudspeaker is placed on its bell. The saxophone can thus both be played conventionally and be used as a filter in a signal chain between speaker and microphone. A transducer is played on the soundboard of the piano and an electret microphone is hung close above the strings. The tam-tam is excited by a transducer placed in the centre of its back and, when playing the tam-tam, the percussionist holds an electret microphone that he or she uses to focus on different areas of the instrument. This is similar to the way the microphone is used in Karlheinz Stockhausen’s seminal work Mikrophonie. Finally, the udu contains a microphone hanging freely inside it and the percussionist holds a small loudspeaker whose distance from the udu’s neck opening alters the feedback. There are thus feedback loops within the interior spaces of the instruments. In the course of the piece, moreover, these loops are extended and different instruments are connected to form new composite spaces.
In Innenraum, sound is not primarily a result of the actions of the performers; rather, it is conceived of as a primary agent that traverses the different instrumental spaces. Since the basic excitation of the instruments is often caused by the feedback or delayed sounds from other instruments, the instruments and the actions of the performers function at times rather as transformations of the existing sound than as its immediate cause. The electronics make heavy use of multiband compression and non-linear distortion techniques, which are also used in Reflexion/Glas.
The piece consists of six large sections, which are characterised by different instrumentations:
A. The piece begins with a 3’30”-long solo saxophone section. At the beginning the mouthpiece is not in the performer’s mouth. After 1’10” the performer takes the mouthpiece in his or her mouth and varies the lip pressure, which changes the acoustic space and therefore the feedback. At 1’28” the performer first starts blowing into the instrument and creates teeth-on-reed sounds and eventually multiphonics. The whole section is a transition from initial outbursts of feedback to steady pitches and finally to a noisy texture that is also diffused over the other instruments.
B. The first part is followed by a 1’35”-long section for solo piano in which the pianist’s actions have the function of altering the electronics by deflecting them in various ways. They function as triggers pushing the electronics into different states.
C. The third section, in which piano and udu play, also has a duration of 1’35”. Both instruments form a common space and the coordinated instrumental actions trigger events and parameter changes. The piano actions are harmonics, scratching the strings, and beating the strings with the flat of the hand. The udu actions are beating the tone hole and subsequent damping of resonances by holding the palm slightly above the tone hole, as well as textural elements consisting of scratching and scraping noises.
D. The fourth section, which has a duration of 1’58”, grows out of the previous section. The udu remains and plays a series of detached gestures and textures that control the articulation of the feedback. They stop, trigger, and alter it. Moreover, the instrumental sounds are recorded and delayed, and towards the end of the section they are diffused over the other instruments, which thereby re-enter.
E. Section five has a duration of 3’20” and is a duo for saxophone and piano. Throughout the section the saxophone’s breath sounds are greatly amplified and played back over the piano; the piano actions are mainly silently held chords that filter the resonances that this causes. The compression controlling the feedback, however, is set up in such a way as to always remain at the border between sounds emerging and dying. There is thus silence in-between outbursts and breath sounds that combine, change in density, and interact in various ways.
F. The final section has a duration of 3’40”. It begins with a solo tam-tam part in which the percussionist moves the microphone according to a described trajectory. After two minutes the saxophone enters and the interior spaces are connected. The saxophone filters what is recorded by the percussionist’s microphone. Finally, the space is further expanded and all three instruments are connected (the only moment in the piece in which this occurs).