Ambisonic Studio
Les fruits du hasard

Les fruits du hasard is a musical project whose purpose is experimenting with stochastic processes as controller for Ambisonic B-Format encoding of mono and stereo sources. The tools used for the random B-Format encoding are developed with SonicBirth, an audio programming application that encapsulates its programming into Audio Unit and VST plug-ins. The modular audio application Plogue Bidule is used for routing the audio signals and patching the SonicBirth-made plug-ins together. The musical elements used in Les fruits du hasard are transformed recordings of solo organ works.

Public performances

Highslide JS2nd International Symposium on Ambisonics and Spherical Acoustics, May 6-7 2010, IRCAM, Paris, France.

Highslide JSToronto Electroacoustic Symposium 2010, August 4-7 2010, Artscape Wychwood Barns, Toronto, Canada.

Highslide JSConcordia University, November 3, 2010, Montreal, Canada.


Les fruits du hasard was born partly out of curiosity and partly out of necessity. It began in 2002 when I wanted to experiment with the University of York Ambisonic VST plug-ins (1, 2, 3). Rather than using arbitrary tones and noises to test the B-Format encoders, processors, and decoders, I thought of using solo organ works, variations on well-known Christian church melodies, that I recorded a year earlier for a CD release. I felt that the variations provided good tonal material and that the somewhat repetitive nature of the compositions would lend itself to some form of deconstruction and various digital transformations. But the project was rapidly put on the backburner because of the tedious process of programming the static and dynamic positioning of numerous sound objects. In 2009, the project was revived because of the development of my random positioning B-Format encoders. The combination of the transformed variations and the use of random panners achieved the aesthetic I was looking for in 2002, but without the need to micro-manage every moment in the music spatialization. Stochastic processes did not replace intent: on the contrary, it became a tool helping the expression of intent.

Les fruits du hasard is presently comprised of three compositions: Variations on Vater unser im Himmelreich, derived from Felix Mendelssohn Organ Sonata No. 6, Six versets sur le Veni Creator, derived from Cinq versets sur le Veni Creator by contemporary French composer Jean-Pierre Leguay and Variations on Es ist ein Ros entsprungen derived from Partita «Es ist ein Ros entsprungen» by contemporary German composer Joseph Ahrens. For the 2001 original source recording, Patrick Wedd played on the Karl Wilhem organ of Christ Church Cathedral in Montreal. The compositions in Les fruits du hasard exist in various lengths, adapted to the listening context like sound installations or concerts. Using Variations on Vater unser im Himmelreich as an exemple, the following description apply to a long version used in sound installations.

Important note: these files use binaural encoding. They are intended to be played back on headphones.

The original Vater unser im Himmelreich melody dates back to the 16th century. In the form that Johann Sebastian Bach and Mendelssohn popularized, the melody can be divided into six phrases. Using the Mendelssohn Sonata recording, each phrase, from the choral exposition and the following five variations, was isolated into an individual sound file, giving a total of 36 files. By using granular synthesis, all the audio files, whatever their original length, were stretched to five minutes. Following the stretching, and by reassembling the stretched phrases in their original sequences, the choral exposition and the variations had now a uniform length of 30 minutes. In this new form, the choral and variations are played juxtaposed, all at the same time: in the first five minutes, we hear the first phrase, but from all variations at once; in the following five minutes, we hear the second phrase from all variations, and so on.

While playing, this 12-channel (six stereo streams) sound file is sent to a processing section that presents various effects to each stream: equalizers, flangers, phasers, and pitch shifters are separately inserted in parallel branches and dynamically applied. Each effect branch is in fact made of two effects and a toggle switch that sends the audio stream in continuously random variable gain and rate to the two effects used in the branch. There's also a global routing network of random toggle switches that precedes the effects processing section, to ensure that, at each playback, individual streams will never be processed in the same manner. Silence is also sent through this routing network to augment the dynamic range of the piece, thus becoming part of the narrative.

Once the routing and processing applied, the audio streams are sent to a spatialization section comprised of 12 Ambisonic horizontal B-Format encoders. Here again, stochastic processes are used as a control mechanism for the B-Format encoding: individual sounds move around totally independent of each other. Slow moving, fast moving, straight lines, curved trajectories, rotations, sounds gradually disappearing at the horizon, sounds suddenly appearing out of nowhere: all these are possible, but their occurrences can never be predicted. All in all, including the spatialization section, the routing network and the signal processing section, more than a hundred random generators are used in this work.

The other compositions in Les fruits du hasard are constructed in the same manner as the previous exemple, thus sharing a common and recognizable audio and musical signature. Their melodies are first divided into basic phrases. Then the same technique of isolating the phrases in each variation, stretching the phrases to the desired length, reassembling the variations and playing them all at once is also done here. The multichannel files are sent to the routing network, then to the effects processing section and finally to the B-Format spatialization section.

Audio file preparation was done with sound editor TwistedWave, granular synthesizer Audio Ease Thonk and sound editor/mixer Steinberg Nuendo. The Audio Units plug-ins used for live performance and responsible for random routing, processing and spatialization were built with SonicBirth. The live performance is done in Plogue Bidule where the multichannel file playback and processing all come together. A Macintosh computer with macOS 10.6 was the composition and performance platform in 2010.

Note: the original paper (PDF) is available from the 2nd International Symposium on Ambisonics and Spherical Acoustics online proceedings.


Highslide JSThe Vater unser im Himmelreich melody divided into six phrases.

Highslide JSThe Veni Creator Spiritus melody divided into four phrases.

Highslide JSThe version of the Plogue Bidule patch that was used at the Paris concert.


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