by Dario Sanfilippo, 2019
commissioned by rotting sounds
production by Thomas Grill

Electronics, algorithm, transducers, resonant bodies

Phase Transitions is a long-form composition for an autonomous adaptive ecosystem operating in real-time which explores the idea of digital deterioration and the behavioural changes in dynamical systems with varying parameters. The work is based on feedback delay networks with nonlinear transfer functions, specifically, saturating units (also known as soft-clipping functions) whose purpose is to ensure stability in self-oscillating conditions but also to make the deterioration process possible.

Saturators transform signals so that amplitude values within a certain range are passed through almost untouched, while values outside that range are compressed never to exceed the limits of the saturators. The more the signals are far from the allowed range (so to speak), the more the signals are distorted (i.e., signals deteriorate), which results in more frequency components being added to the network.

The feedback coefficients determine how much of a signal is fed back into the network, while the lengths of the delay lines determine after how much time a signal will start to recirculate. The first parameter is responsible for the deterioration process as it affects the magnitude of the signals going through the saturators, which will also change the spectral output because of the added frequencies, while the second parameter is responsible for reinforcing or dampening specific frequencies in the spectrum. These are the two varying parameters in the system.

The delay lengths are chosen as powers of prime numbers. It is enough to know that that will favour a homogeneous distribution of the energy over the whole spectrum. The initial feedback coefficients correspond to the self-oscillating threshold of the network. It means that, after being initiated, the network could theoretically operate endlessly without any external energy being provided. In this case, the network is initially triggered by an ideally short impulse (a Dirac) that sets the system into an operating state, producing sparse tones.

The system is coupled with the environment through a microphone (input) and a resonating wooden bench (output). The signal from the microphone is processed so that some information is extracted and used to pilot the delay lengths. The analysis window of this process is one hour. It means that there is no immediate cause-effect relationship between what happens in the environment and the output of the system: theoretically, a perturbation in the environment will reach its maximum effect after one hour, but the system’s output is continuously affected by the past environmental conditions.

The feedback coefficients are set to grow of a magnitude of 2 in about three months. Roughly, that is the limit after which the saturators will be full and will have no further effect except producing broadband noise. That is indeed what sets the life span of the system.

A nonlinear system with several interacting feedback loops and varying parameters is expected to generate phase transitions. These are a radical change in the state of the system, and they show particularly rich and nontrivial dynamical behaviours. The last and perhaps most important aspect of the work is an adaptive mechanism for the growth of the feedback coefficients used to explore microscopically such behaviours: when a phase transition is detected, the feedback growth is radically decreased to almost freeze the current state variables until the transition is over. Interestingly, the detection process itself can either trigger or suppress a transition, resulting in a system that, by observing itself, will also affect its behaviour, which is what generates the formal development of the piece.

Archive

You can find archived sounds of the piece (1 min per hour) at the Rotting Sounds Archive.

by Thomas Grill, 2019

Ink print on paper, acrylic glass

The work is a printed representation of the soundscape recorded at the auditorium at midnight of March 1st, 2019, the beginning of metereological spring. In the still of the night, a nightingale sings outside in the garden, its song leaking through the windows into the reverberant space of the auditorium.
The audio recording is in the form of a monophonic 1-bit encoding, a very high quality audio representation consisting of a stream of bits. The bit stream has been printed as a spiral of black and white segments, starting in the middle of the circle. It can be converted back to audio by a simple decoding process. However, imperfections in the print and through wear and dust on the acrylic glass will change the visual appearance over time, therefore also changing the audio content.

by Mario de Vega, 2019
commissioned by rotting sounds
production by Thomas Grill

Operating System, script, silicon carbide crystal, electric power line

Intermission is composed of an electronic system and a rudimentary suspension mechanism. Its principle is simplified as code written to analyse and retard an audio signal using the microphone input and segments of a computer interface as engines. A piece of silicon carbide crystal, suspended from the ceiling, interacts with the feedback of the system itself, acting as a gate that increases and decreases the fluctuation of a digital signal.

Special thanks to Alberto de Campo and Hugo Esquinca.

Archive

You can find archived sounds of the piece (1 min per hour) at the Rotting Sounds Archive.

by Juliana Herrero and Thomas Grill, 2018/19
commissioned by rotting sounds

Steel cable, color, acoustic transducers, digital sound processing, text

The “Antenna” installation creates an interface between sound and its environment. It transmits sounds generated from encoded text. These acoustic vibrations are resonating through the networked body of the artwork, amplified and broadcasted into the surrounding air. The artwork recites the text of “The Art of Noises” (L’arte dei Rumori), a futurist manifesto written by Luigi Russolo in a 1913 letter to his friend and futurist composer Francesco Balilla Pratella.

An audio codec translates the individual letters into musical chords, which are in turn sent over the wire sculpture. These vibrations are modified within the filigree structure by the environmental conditions — wind, rain, dust, birds sitting on the wire. At the other end of the wire network, the sounds are picked up again and translated back into text. This process can be followed on a small display. By the time, the environment of the sculpture inscribes itself into the text by disturbing single bits of the manifesto, slowly turning it from readable text into environmentally informed noise.

Archive

You can find archived sounds of the piece (1 min per hour) at the Rotting Sounds Archive.

by Klaus Filip and Thomas Grill, 2019–2021
commissioned by rotting sounds

Digital audio via laser beam

A musical motif in just intonation consisting of pure sine tones serves as starting material. It modulates the intensity of a laser beam. The laser is sent through the room with a mirror several times and finally directed to a phototransistor. On its way through the room, the optical signal is disturbed by the dust present in the air. Individual bits are changed. The dusty bitstream overwrites the memory of the original signal, is sent to the source material and again through the room.
This is repeated over hours, days and months and can be heard via headphones.

Archive

You can find archived sounds of the piece (1 min per hour) at the Rotting Sounds Archive.

by Nicole Krenn and Thomas Grill, 2019
commissioned by rotting sounds

Paint on paper, generative audio composition

The installation “Fields of Haze” claims the western corner of the auditorium with 31 paper-covered stretcher hangers suspended from the ceiling. The pale color surfaces break the view to the back wall of the library of the Music University – where thousands of scores are stored – on the other side at this point notes for ensembles with several pianos. In very slow succession, chords seep through the wall and emerge through the mists. In short, they are clearly audible, but run quickly and spread out over the paper walls. Gradually, they blend into a vague tonal color that settles permanently in time and space.

Architecturally, the installation presents itself as a flatly dissected image of single images that spans the corner of the room, detached from the classical hanging on a flat wall. Through its permeability, it opens the room into the depth, but on the other hand, it offers a homogeneous radiating surface for the sound. At the same time, the paper carries both a visual and an acoustic color, in a movement that moves both spatially and temporally.

The piano chords represent the composition Véxations by Erik Satie (played by Jaime Wolfson), whose prescribed 840-times repetition at the chosen tempo would take several weeks. The individual sounds melt within a few seconds through spectral erosion processes, as they are also manifested in the MP3 compression and condense into swathes of digital sound vapor.

Archive

You can find archived sounds of the piece (1 min per hour) at the Rotting Sounds Archive.