A metal string, tighten by the weight of a drum is connected to the output of an amplifier. A microphone connected to this amplifier feeds the sound of the string back into itself as analog signal which reacts like a non-linear diffuser. The drum is the acoustic medium between the string and the microphone. Different positions result to diverse resonances of the feedback.

{kind: caption, keywords: [drum, string, amplification, microphone, feedback]}




Improvisation performance (2019)


This performanc explores the phenomenon of sonic synchronization between two heterogeneous feedback systems by means of improvisation. The application of chaotic systems to creative musicking is associated with spontaneous play, since this practice can deal with the intractable traits that characterize such systems (non-linearity, non-periodicity, unpredictability, unrepeatability). Synchronization is a well-understood phenomenon where chaotic systems with different trajectories and oscillating frequencies, converge to identical ones when coupled. The “confluent currents” performance investigates this unique feature, by interconnecting two different feedback systems (analog-digital), allowing their idiosyncratic signal flows to exert influences to each other and resonate at unexpected frequencies.


The first feedback system consist of various electromagnetic string instruments that re-inject feedback signals into the strings, creating evolving resonances which depend on the contraction and expansion of the strings due to alterations in temperature. The physical manifestation of this system obliges the performer to make delicate gestures in order to locate the “resonant spots” of the instrument’s components. The second feedback system is a digital generative feedback network implemented with the PureData programming environment. A far-from-equilibrium drive of the non-linear oscillators produce mellifluous sonic streams of explosive and recalcitrant character.


The performers try to push their systems towards equilibrium states, where the internal dynamics settle to steady frequencies. Then the phenomenon of synchronization takes place, with the two frequencies starting to approximate a harmonic relationship. Sometimes this proximity cannot occur due to unconformity between the current individual states. After a successful or failed synchronization, the performers will search for new equilibria, by perturbing the current states and traversing unexplored routes of tumultuous activity.

{kind: paragraph, function: contextual, keywords: [_, complex systems, frequency, coupling, string, instrument, electromagnetic, feedback network, pure data, performance, perturbation, equilibrium]}


In this improvisation session only the digital feedback system is animated and the sonic output is the result of its internal dynamics (input is muted). Each non-linear oscilator is rendered to one speaker (left and right) and contain four feedback pathways. The two feedback pathways are modulated by the energy signal (RMS) of its own oscillator (self-modulation) while the other two are modulated by the energy of its twin. This schema achieves a delicate coupling that allows the autonomous behavior of each oscillator to unfold and at the same time a subtle interdependence that makes possible the phenomenon of synchronization. The performance consists of minimal adjustments of some parameters that drive the system away from equilibrium states. 

{kind: caption, keywords: [feedback, network, system, coupling, synchronization, modulation]}

meta: true
event: almat2020
kind: essay
date: 200919
author: [Kosmas Giannoutakis, Arthur Lanotte-Faure]
place: Online

keywords: [synchronization, feedback, system, feedback system, improvisation]