Listening space/ perceiving space:
the forest inside the concert hall
Cursus 2 Ircam Project
Poetic inspiration (readings of Harrison-Michelet-Vico).
The first chapter of Robert Harrison’s Forests[i], entitled ‟D’abord les fôrets: les géants de Vico”, talks about the thought of Italian philosopher and historian Giambattista Vico. In this chapter he evokes some interesting notions about the first men in Vico’s vision that had captivated me:
- This life plunged into the matter (forest as the matter and as his ”wilder state”)
- in this discovery process of the first men, the author qualifies them as poets as a first and intuitive state of what today we consider as philosophical concepts
- the opposition between the forest as an ”opaque” and enchanted world who challenges the city as dominant institutions
What was interesting about these concepts is how precious and innovating they could be in Vico’s era (1668-1744) and how valid (in other perspectives) they seem to today’s age.
In Michelet text about Vico’s thought and the first men, he introduces this subject by talking about a Greek word ‟Hyle” does not just mean ‟matter” but also ‟forest” to show how connected these concepts were back then.
Listening space inside directional music speech
– Recording sounds with sound field micro[ii]and musical ideas:
The first steps of the work were to form graphics and recordings – listening to forest soundscapes and after city soundscapes or more precise noisy objects from these soundscapes. In the forest I was looking for surroundings ‟scènes” with various wind layers and also little sounds as ‟wind between the trees,” branches crackling and leaves rustling.
In the city I was interested in very noisy, intense and dense sounds as construction work, trains and metros, but also in different event frequency and mixed soundscapes as on Place de la République or Buttes de Chaumont park (where I recorded also the cascade from different angles and distances).
This listening analysis also provides me harmonic material for instrumental writing (using perceptual Masking Effect analyses[iii]).
The subject of introducing ‟space listening” without musical directionality but in a 3D listening, in the middle of the piece, progressively from a more directional gesture speech was one of the interesting things about the research connected to the piece.
Technological researches connected to the poetic idea (developing some ideas):
These poetic ideas were connected to my previous sound idea of the piece: big density of sound matter in space and the recreation of ‟virtual forest soundscape” with string quartet writing (creating previously noisy-wind sound layers). I have also worked with synthetic ‟sound design” sounds of the application ‟Spad” by Charles Verron[iv], using especially different synthetic wind sounds.
These poetic images and sound idea of matter density were entirely linked to the possibility of working in Spatialisation system ambisonics in 3D[v] for the project.
The idea of confronting noisy and ‟agressive” sounds at the end part of the piece is intended to create this opposition of sound worlds. I have worked with the resynthesis of complex sounds as trains, work sounds using models from analyses and transforming these models with Open Music library (OM-Chroma) in differed time.
In the real-time domain I proceeded to analyze instrumental sounds in real-time with Max[vi] object iana (analysis and extraction of significant perceptual components based on Terhardt algorithm[vii]) and after processing this data was used to drive a re-synthesis process in real-time (inharmonic or spectral exploded).
– Granulation mix of forest and city sounds (Catart[viii])
To also attain this big dynamic contrast between sections the event frequency builds up in the last part up into an accumulation of granular sounds (using Catart). In this application I was able to mix sounds of very different types and origins and classify them according to different parameters (noisiness, brilliance, pitch, loudness…)
– Following a sound timbral description in real-time
Another idea of tools research was to continue to explore the connection between ‟fine” music performance and real-time dynamic transformation of gesture. I have been working with ‟Ircam descriptors”[ix] and their possibilities in real-time captation to perform dynamical filtering transformations to the string instrument sounds.
Musical writing exploring in form and directionality: connection between string writing and electronics processes and materials
Constructing form – string quartet musical writing
- Matter: gestures /harmony /textures-density
In the first section from the poetic idea ‟live plunged into matter (in raw state)” I worked with timbric transformations, in instrumental writing as in electronics, using different string techniques (that creates a palette of distinct spectral densities): from harmonic sounds to molto ponte sounds, half-pressed (left-hand) to half-distorted sounds (string with a metallic clip). These gestures, of which some are invasive, create a ‟raw” and heterogeneous sound mass -filtered and distributed in space after by the electronics.
I also worked with some melodic motifs always linked to timbre gestures. For the harmonic material I used ‟chord-torsion transformations” from material extracted from city recordings, also using a first fractal subprocess to create more dense chords. For axis pitches I used obtained pitches with more spectral weight (from Masking Effect analyses).
- Creating space (sound layers, as in a forest sound scape): transformation to cyclical events/ periodicity of these events/ melody of harmonics (over harmonic background) ‟listening the space”
In this second section, after a cyclic noisy gesture that allows to create a new and more distant layer sound (as a wind background), gestures become gradually less dynamic, more flexible and fine. Cyclic appearances began to overlap with these fine gestures, as crackling or rustle sounds.
A kind of ‟quiet forest soundscape,” with different wind layers in the distance, appears and takes up all the space in the hall. Before the irruption of the third section an emergence of these harmonic melodies appears and expands over the listeners with the transformation of fine metallic resonators. The resonance of the simple base chord is discerned from afar.
- City objects irruption: resynthesis with string quartet chords /granulation-sound accumulation / big density sound (as cascade) and sound concentration over one pitch (central pitch)
For the last section the string quartet is less predominant and has a role of ‟harmonic accompaniment” with the electronics tape (recorded sounds and resynthesis). In this case I also use pitches from harmonic analyses of city but in some cases they appear just ‟masked” sounds (sounds that are in the sound analysis but with a spectral weight of 0.) in counterpoint.
After this mixed passage there is a rhythmic accumulation exposed as a dialogue between articulated string sounds and electronics. That leads to a final big and granulated sound wave that is mixed with the appearance of very noisy and intense sounds: the cascade. This buildup unleashes a sound concentration on an axis final pitch by all the string quartet instruments.
Electronics is triggered by pedals from the musicians (pedals connected to musical gesture):
– real time processes: analysis, sound transformation, resynthesis and spatialization, with the connection between two computers via OSC connection (one computer just for ambisonics spatialization calculus)
– differed prepared sounds: resynthesis, mix sounds tape (end), wind synthesis sounds, resonators, etc.
In two concert distinct experiences, we adapted ambisonics parameters to the hall, in very different spaces with contrasting reverberance: “salle de combes” Royaumont and Vitaasari Church (“Time of Music” Finland). Both performances by Quatuor Diotima.
This project has been done thanks to advices from Grégoire Lorieux, Hèctor Parra, Markus Noisternig (Acoustic and Cognitive Spaces Team of Ircam) and special memories of Sound Engineer Melina Avenati who has worked in the recreation of virtual space and in the recording sound.
* * *
[i] Forêts: Essai sur l’imaginaire occidental. Robert Harrison. Champs Essais
[ii] The Soundfield microphone is an audio microphone composed of four closely spaced subcardioid or cardioid (unidirectional) microphone capsules arranged in a tetrahedron.
[iii] The masking effect analysis is based on the Terhardt algorithm. Our perception of sounds is dramatically dependent on the characteristics of our auditory system – not to mention our whole cognitive apparatus. These characteristics can be modelised. The Terhardt algorithm takes this model of auditory pitch perception into account to deduce the auditory pitch perception from the sound wave’s Fourier spectrum. http://support.ircam.fr/docs/AudioSculpt/3.0/co/Masking%20Effect%20Intro.html
[iv] http://www.charlesverron.com/spad.html[v] Ambisonics is a full-sphere surround sound technique: in addition to the horizontal plane, it covers sound sources above and below the listener. https://en.wikipedia.org/wiki/Ambisonics
[vii] Harmonic: A Psychoacoustical Approach. Richard Parncutt. Springer-Verlag
[viii] Concatenative Synthesis http://imtr.ircam.fr/imtr/CataRT
[ix] Technology for the automatic extraction of digital descriptors from an audio signal, the gathered data represents the principle useful characteristics of the sounds given their classification and comparison. http://web4.ircam.fr/1041.html?&L=1