LUIGI MARINO

musician

Network 2 (2018)

7-relationship-network

Performances:

  • 13-Apr-2018 - Spektrum, Berlin
  • 9-May-2018 - DeMontfort University, Leicester - Performance and lecture
  • 15-Jul-2018 - Iklectik, London
  • 27-Nov-2018 - Institut für Elektronische Musik, Graz - Performance and lecture

Network 2 is a work that uses the computer's analytical capabilities to surround the performer's gestures with an immersive synthetic landscape. This landscape requires no intervention other than the sounds produced by the performer for its whole development. These sounds are converted into a wide variety of data which are then recombined to generate all the aspects of the computer's response. The computer's output is entirely synthetic and there is no use of sampling or timeline sequencing.
The sounds used are sometimes referential to more popular genres: there is glitch, synth patterns, percussive gong-like sounds. It's not an intellectual operation, those sounds belong to my experience, but it is also a chance for me to explore a very particular cut about emergent behavior. We are starting to get used to the "alien" sounds of machines, it is almost if we expect the machine to sound that way. What happens if the machines use sounds that we consider socially codified? What happens if the machines behavior proposes with an unpredictable logic sounds that evoke a vague sense of familiarity? What happens then if these sounds betray our expectations?

This work is divided in two distinct sections. The first one is responsive to the sounds produced in that exact instant, but its response is generally tangential: the spectrum analyzed is spread over a larger timespan, and often the computer recombines data coming from sounds produced at different time. This part deals with active participation. The second section uses all the data accumulated during the first section to generate an independent landscape with formal ties to the sounds produced by the performer in the first section; although the relationships are mostly unintelligible. The result of the mapping process is mostly relegated to the spectral components of one single sound that is then repeated, lengthly. In this part I'm simply a spectator happy to be surprised by the machine's behavior. The length and repetition is a way to cope with that complex process of understanding how much I care about my expectations.

In this version I'm driving the system with a classic from the '70s, the crackle box. The crackle box is a circuit designed by Michel Waisvisz in 1974. The original circuit consists of an operational amplifier whose connections are brought on the control surface, and left open. The user, touching them, closes the circuit using the body as conductor. The sounds produced are related to the resistance of the body, and the amount of pressure applied on the connectors. The classic crackle box used the integrated circuit LM709. Unfortunately the LM709 is not that easy to find, so instead I used the schematics of John Richards bed of nails, which uses a far more common IC, the LM358. The op amp inside the LM356 is more stable and less prone to surprises, but in the bad of nails this is compensated using both the op amps on the IC, basically creating two crackle boxes feeding back into each other. Furthermore, there is a white noise generator made amplifying the background noise of a small 10 Ohm resistance connecting pin 2 and 3. The connection is done manually, pushing with the finger the resistor on the pad, so it's possible to control the white noise in a fairly performative way.


Description of the relationships

This is mostly a memo for me to remember all the steps necessary to bring the piece to an end. It is also a diary where I describe all the relationships I develop, so that they can be reused for successive pieces. The terminology sometimes might sound obscure because it is an application of a theory that I'm currently developing loosly based on the actor-network theory. I'll link it when it will be in good shape.


• Relationship 1 - The glitchy synth that responds first to the input.
This relationship is fairly direct in terms of rhythm and pitch, and has a generative behavior in its variations and spectral content. The onsets of the synth and its pitches are a replica of the input signal with a 8-second-delay, enough to cancel an excessively direct perceptual association. All the glitchy variations are independently generated by the computer, but they have a simple performative relationship with the input: the amplitude threshold of the input, on its way up, flips the state of a switch that controls many generative processes, basically turning on and off most of the variations. The synth is also generative in timber cause there is a preset morphing driven by a transition that is random in time.

Activating condition - Detection of 1st event.

Ending condition - Detection of landmark 1.

Occurrence - 8-sec-delay applied to all the onsets.


• Relationship 2 - The slowly moving background.
This relationship is very tangential and uses spectral techniques to relate the spectrum of the input to the spectrum of the synth. Every 6 seconds an FFT frame of the input signal is taken, and some of the frequency/amp pair of the most prominent partials are assigned to banks of resonant filters. The banks are six and fade into each other providing a slow and dense morphing. The selection of the frequency/amplitude pairs follows a user-defined pattern based on one important parameter: how much the spectral content of the filter banks have to resemble the input (a variable tangentiality). When a spectrum more resembling the input is desired the program uses the most prominent partials; when a spectrum more tangential is desired, the program discards the loudest and selects the quietest ones. The overall amp is always normalized but it preserves the amp ratio of the FFT partials, setting the amp of the loudest used partial to 1. The resonating filter banks are excited with white noise. Slow random automations are used to control the amp and the transition from a flat sound to an impulse-like one. The decay of the resonant filter (here you can think of it as a normal Q) is directly related to the noisiness of the input signal, so when the input is more similar to white noise the decay is high and viceversa. This relation requires a continuous input, so when there is no sound to be analyzed it uses a silent loop created with the last part of the input sound.

Activating condition - Detection of 9th event.

Ending condition - Detection of landmark 1.

Occurrence - Continuous.


• Relationship 3 - The 2 synths that respond to glissandi.
This relationship links the pitch and above all glissandi of the input signal, to the gliding synths. It uses two kinds of buffer recording to store some user-defined parameters: the spectral centroid and an on/off signal when there is input sound. One kind of recording opens the buffer and closes it in correspondence with the amp threshold, so a buffer with a defined length is recorded every time there is an event in input and can be used right after. A second kind of buffer recording is continuous and these data can be used even if the buffer isn't closed, respecting the condition that its reading speed isn't faster than the real sound (reading index <= 1). This allow to sync some buffer based operations with the attack of the input sound. The use of these buffers and the related onset of the synth is triggered using probability: the reading can start in correspondence with the attack of the input sound, a few ms after, in correspondence with the end of the sound, or after the end it can wait for a random delay. The spectral centroid recorded on the buffer is applied to the pitch of two additive synths both displaying independent behavior in many other parameters. The probability works independently for the two instances of the synths. The reading speed of the buffer is random and often is extremely slowed down. On top of that there is the possibility that the reading freezes so that the timbral independent movement of the synths can emerge from the sustained sound.

Activating condition - Detection of 15th event.

Ending condition - Detection of landmark 1.

Occurrence - Probabilistic, related to the amp threshold.


• Relationship 4 - The 3 static synths with sharp attacks.
This relationship is fairly direct and uses simple information like amp threshold. It involves three instances of a synth: one uses very low frequencies, the other two very high ones. It is all about the minimal generative behavior of the synths. Again the onsets are probabilistic and they work similarly to the ones described in R3, but they are less probable.

Activating condition - Detection of 15th event.

Ending condition - Detection of landmark 1.

Occurrence - Probabilistic, related to the amp threshold.


Relationship 5 - The electro patterns.
This relationship is the one responsible for those patterns that provide some melodic and rhythmic material. The pitches of the patterns are the most prominent partials of an FFT frame. When the relationship is called, a FFT frame is taken from the input sound, and a random pattern is chosen probabilistically. If for example the pattern has a rhythm of 11 beats, the most prominent 11 partials of the FFT frame are used as pitch material for the pattern. The pattern also can have one or two notes that are two beats long. The pattern is looped and the loop can change during the occurrence of the relationship, but with a very low probability. Each occurrence has an overall duration that ranges from 30 to 60 sec.

Activating condition - Detection of 15th event.

Ending condition - Activation of relationship 6.

Occurrence - It occurs when the input sound is longer than 6 sec. After each occurrence the module must wait 40 sec to be used again.


• Relationship 6 - The singing one.
This relationship responds directly to the spectral centroid of the input. The centroid is mapped directly to the pitch of a recursive FM synth, and at the same time it is recorded into a buffer. When the input sound stops, the buffer is looped and continues to control the pitch of the synth. The loop goes through a series of generative processes: it can remain constant, slow down, or speed up. Some parameters of the synth can be changed during the looping time. When they change, they follow a direction and cannot go back until a new loop is used.

Activating condition - 3 occurrences of relationship 5.

Ending condition - Activation of relationship 6.

Occurrence - Continuous.


• Relationship 7 - The percussive sound in the last part.
This relationship alone occupies the entire second section of the work. It is different from all the others in that it uses the data stored in the long term memory of the system, and operates when the performative gestures are over. This is one of the most tangetial relationship possible. The time intervals of the percussive synthetic sounds are the reverse of the intervals of the onsets of the sounds analyzed in the first section. Their spectral content is a result of data recombination of the spectra of the analyzed sounds: the most prominent partial of the last 18 events are used to create the spectrum. They are transposed in range to make sure that the spectrum is balanced but they are left unaltered, so that any possible harmonic or inharmonic relationship is the result of an emergent behavior. The overall duration of this section is the smaller part of the golden ratio of the overall duration of the first section.

Activating condition - After the landmark 1 has been detected, wait for the detection of an event that is at least 6 seconds long, when that happens, wait until there is no longer sound, than wait for a duration that is equal to the detected event, than activate the module.

Ending condition - The condition is met when the internal clock of this relationship that starts with its activation is major equal to the duration of the first section multiplied by 0.382.

Occurrence - Continuous.