First octophonic tests
In the summer of 1979, the system was ready for its first «in situ» tests; in a large room, with four speakers attached to the ceiling and four more at floor level.
I had been using the device for some time in quadraphony.
Since occupancy was low during the summer period, I reserved the main concert hall of the faculty for a block of consecutive days.
The room was flat, with no fixed
seats, so the entire space could be freed for our tests.
I borrowed eight high quality loudspeakers from the Electro-acoustic department and we fastened four of them, at the correct angle, to the ceiling of the room (take note of the ladder at the back of the following photo) with the other four speakers right below them in order to produce an eleven foot cube.
Four high-quality stereo amplifiers linked our system to the loudspeakers.
The octophonic transducer in action
Photo of the three-dimensional opto-electronic transducer.
You can see the cube, made of aluminum tubes,
with towers extending in the three x, y, z directions. The opto-electronic sensors are placed at the summit of each tower. Any movement by the wand, with its luminous tip, is transmitted to the main unit as three coordinates.
Université de Montréal, summer of 1979
Calibrating and testing
Since each module in our system offered extensive calibrating capabilities, we worked several days at making sure every voltage corresponded to Hubert's calculations.
Testing the octophonic system
3D opto-electronic transducer seen from the back.
The main unit, with its vertical circuit boards, is directly below it,
next to four stereo amplifiers.
This equipment is situated inside an 11 foot cube
formed by eight loudspeakers.
Université de Montréal, summer of 1979
The system passes the test
An octophonic system has to be symmetrical on all three axes.
A figure generated in one part
of the cube has to be replicable in any other one.
We found that the system performed in the way that was expected, both in electrical tests and in listening tests (described below).
four ceiling loudspeakers
After this summer test period was over, we cleaned the room of the equipment we had brought in, but decided to leave the four ceiling loudspeakers in place so we could keep on testing during the fall session.
Attaching and orienting them had taken some time and their presence wasn't a disturbance.
I was informed, at the start of the academic year, that the speakers had been stolen.
This event had a disastrous effect on the project.
How octophony sounds
Hearing the sound moving freely in 3D space is both exciting and intriguing, the effect is new to our ears.
It makes you focus your attention on what is happening behind, above, below and all around you.
Of course, the perception we have of a sound differs greatly depending on its provenance in relation with our outer ear.
So, even if the octophonic system is entirely symmetrical, the human ears have evolved to privilege sounds coming from the front and at their height.
The perception of motionless
and moving sounds
Studying the «movement» of sound in tridimensional space was the title of the whole project, not its fixed positioning.
This is probably because, long before
building anything, I was convinced that:
|Movement improves our perception
of a sound's position in space
Static sounds, those that stay in the same place for an extended time, are much harder to localize in space than those that move.
It is as if the positional change alerts your brain
of the sound's presence and it then keeps track of its trajectory.
Our listening tests confirmed this theory.
We soon found out that the brain could only follow a sound's movement up to a certain speed.
Passed that speed, the brain gives up and considers the motion as a swirling effect.
For example, if the sound follows a simple circular pattern around the room, its position can be easily followed when each rotation is done in two seconds. The slower you go the better the perception gets, up to a limit.
At faster speeds, above one rotation per second, it becomes blurry and punctual detection ceases at around half a second.
Even if localization is lost at higher frequencies, the motion gives the sound a new and unique dimension and has proven to be, to me, an interesting compositional tool.
Pre-recorded or live music
While composing with the system, I found that performing the music live at the same time I was directing it in space yielded superior results, when compared to using pre-recorded music.
Obviously, giving the spatial dimension equal importance
with sound creation helps localization, mostly when they are generated simultaneously.
High and low pitched sounds
We were well informed, before starting this project, that the perception of a sound's localisation, in humans, diminishes as its frequency goes down.
This is why only one central loudspeaker is used for bass in several stereo configurations.
We also toyed with the idea of
excluding low frequencies from our system, but we decided otherwise.
This ended up being a wise decision because I found that I could follow some low sounds around quite well.
With motion, especially when a musical pattern is present, the position of low pitched sounds becomes more perceptible.
This phenomenon can be further enhanced by using localisation helpers, as described below.
Attack and sustain phases
It is important to point out that the localisation of a sound in space is best performed during its initial onset, or attack period.
The first portion of each musical note is very identifiable because its volume is at its loudest and that several of its parameters vary very quickly.
Simply repeating a sound, even when changing
its pitch, will retrigger its positioning by the brain.
Later on, when the sound is sustaining, localisation is diminished and can be lost totally if no change in timbre is detected.
Therefore, it is best for the composer, when using long notes, to keep on changing the sound's parameters while they are sustained.
the sound-position interactions
I also immediately noticed that localization was greatly enhanced when one of the music's parameters followed the positional values for one of the three axes.
The simplest example I can give is having the frequency of the sound go down as the wand goes down, and up when it goes up.
The simplest sound-position interaction:
the z coordinate controls pitch
When the sound goes up and down along with its position in space, localization perception is improved to a great extent.
This relationship seems to be obvious to the human brain.
Inverting or modifying the orientation doesn't cancel this predisposition, but alters it.
Inverted and modified orientations
Other sound-position interactions
Once this concept is understood, it can be applied to any controllable sound parameter.
Since the x, y and z coordinates for each voice were readily available as control voltages, all I had to do was to plug them in the modulation input of any synthesizer module and it would respond to spatial positioning.
All these «sound-position» to
«sound-parameter» relationships are helpful in localizing it.
As a result, by hooking up the three spatial coordinates to a synthesizer's various modulation inputs, I could set up sounds that were different in every part of the space.
The characteristics of a sound traveling along this figure
change depending on its position in space.
In fact, the sound would be different at any point inside the cube.
In some configurations, the sound can become muffled, muted and can even disappear completely in some parts of the cubic space.
The listener's brain fills the gap
While this phenomenon would prove unacceptable
for most types of music, in the case of 3D motion, it almost seems natural.
The brain will make up for the missing section, as long as it isn't too long.
Two, three and four
As expected, having two or more sounds, each one with its own tridimensional spatial travel, at the same time inside a cube makes their localization more difficult.
How well you will perceive their location depends on how different the sounds, their positions and their motions
are one from the other.
Slower moving ones are better identified.
This being said, aesthetically interesting composition only begins, for me, when two or more voices are used. The listener's brain may not be able to follow their whereabouts, but the air of the room
moves and pulsates along with them.
Mirrored 3D motions
Having four sounds doing completely different movements is interesting, but linking the spatial paths of some voices together heightens their perception and impact.
Once one spatial trajectory is recorded on tape, its three x, y and z coordinates can be resent during playback to a second sound, but this time they can be inverted, modified or rerouted.
for sound 1
||The spatial coordinates
of sound 1 are reused
for sound 2,
but one of them
Mirroring offers a way to synchronize, combine and transform spatial figures; creating multi-voice 3D sound patterns.
The «center proximity» coordinate
Not all points are equal inside an octophonic cube.
The ideal location to place your head is right in the center.
may also be adequate, but you get an altered version of the music and figures.
When a listener's head is in the center
of the cube, all the sound's movements and figures are perceived from that vantage point.
Some sounds are close while others are distant.
There are several distinctions between sounds that are near you and those farther away. For example; their phase (in relation with your ears) changes, their reverberation characteristics differ, their timbre is modified, ...
The value of the «center proximity» coordinate
varies as the sound moves away
from the center point.
The «center proximity» coordinate can be used by a composer in several ways to enhance the distinction between sounds that are moving towards and those moving away from the listener.
Synchronizing music and figures
We had included an external clock input on the 3D figure generator so it could be controled by other sources such as sequencers and synthesizers.
This has proved to be an essential feature.
It permits the interlocking of individual notes with their position in space.
One bar musical pattern synchronized with a circle figure.
Every time it repeats, the notes stay in the same place.
The length of the sequence, its musical content and the figure it follows can all be chosen by the composer.
Both pattern identification and spatial position recognition are helped by synchronisation.
Even with non-repetitive musical motives, it allows for each bar to start at the same
location and for each beat to have its own region in space.
Composing with the system
As explained below, I used the system mostly in quadraphony.
I composed with it for several hundred hours, during a two year period, in a quadraphonic environment, with a four track tape recorder at the Faculté de musique.
I also had access to a large modular analog synthesizer with a keyboard and a professional mixer.
I was composing a 20 minute piece of music dedicated to exploiting sound movement.
As a composer, I have never let myself be restrained to a specific style; I feel free to go anywhere I fancy.
For this piece, I chose to work with electronic sounds rather than using acoustic instruments because they permitted a better interaction between the sound and its position in space.
I ended up doing a type of music I had never imagined before.
Since every aesthetic musical decision I made took into account the beauty of the spatial figure that accompanied it,
the result was like a musical sculpture.
Each voice is comparable to dancer on stage; with several of them, you can create choreographies.
But with tridimensional motion, each musical track becomes more like an individual plane during an air show.
The people watching these shows enjoy the patterns and tightly choreographed motions the planes make.
However, if the planes didn't leave a smoke trail, the figures they produce would be much harder to perceive.
I also believe that our brain is more inclined towards visual pattern recognition than sound motion ones.
Finally, in octophony, since the head of the listener is situated in the center of the action,
the figures are perceived as if he was immersed in them.
Composing for moving sound
I really enjoyed the excitement motion brings to even the simplest sound.
Filling out the empty space became more of a preoccupation.
Since the sound surrounded me, I felt part of it.
I ended up doing about twenty short «musical animations».
The aesthetics of moving sound
As I composed these pieces, I became aware that the music I was making would not be appreciated by my teachers.
I was facing new musical surroundings
that forced me to innovate and to expand my definition of music.
A simple sound, moving around in space while its timbral characteristics are
changing, may give interesting aesthetical results.
I was designing multi-voiced choreographies and
sound sculptures that had little in common with the classical, popular or contemporary music languages
What I was creating could not be written
down or analysed with traditional methods.
Most musical genres, when recorded in stereo, can still be enjoyed on a monophonic system.
This was not the case of what I was doing; it had to be experienced in the proper environment for it to make any sense.
Four loudspeakers instead of eight ...
A four track tape recorder instead of an eight track ...
I know that the Faculté de musique de l'Université de Montréal is now wonderfully equipped for recording, but that wasn't the case in the 1970's.
In 1979, I wrote the following letter to the dean of the faculty, asking that they buy an eight track tape recorder.
Le 15 août 1979
Monsieur le doyen de la Faculté de musique
2375 côte Sainte-Catherine
Monsieur le doyen,
J'ai déjà, il y a près de deux ans, fait appel à votre aide, au sujet du projet «Étude du déplacement tridimensionnel du son». Il s'agissait, à l'époque, de trouver des fonds pour rémunérer M. Hubert Caron, ingénieur, qui travaille avec moi. Je suis étudiant en rédaction d'une maîtrise en composition.
Le projet comprend trois phases:
1- Construction des appareils.
2- Étude du déplacement tridimensionnel du son.
3- Composition d'une pièce en «octophonie».
La première phase, qui nous aura demandé plus de 2,000 heures de travail, sera terminée d'ici deux mois.
Le but de cette lettre concerne les deux phases subséquentes. En effet, dans notre système, les trois signaux de position (x, y, z) sont traités indépendamment du signal audio et «encodés» (multiplexés) sur une piste parallèle à la trame musicale. Voici un diagramme indiquant la répartition des pistes d'une pièce à quatre voix distribuées dans l'espace.
Signal audio; 1, 2, 3, 4
Coordonnées de position: 1, 2, 3, 4
Évidemment, ce système exige l'utilisation d'un magnétophone ayant huit pistes au minimum, et la faculté de musique de l'Université de Montréal n'en possède pas encore.
Je demande donc l'achat d'un tel appareil qui serait aussi très utile au travail de composition électro-acoustique. Connaissant les difficultés que cet achat pourrait occasionner à la faculté, je suggère l'achat d'une huit pistes semi-professionnelle de marque Tascam et de modèle 80-8 dont le prix institutionnel se situe aux alentours de $4000.
Je me tiens à votre entière disponibilité au cas où les renseignements fournis dans cette lettre s'avéreraient insuffisants.
Veuillez agréer, monsieur, l'expression de mes sentiments les meilleurs.
27xx place Darlington, apt. 24
The project lasted over three years .
Instead of the 200 hours we thought it would take, we invested thousands.
Except for the initial $2,000, Hubert never was paid afterwards.
Though the expenses weren't considerable, they ate up my budget as a student.
We did it because we enjoyed building and inventing things.
Octophony was a challenge, so we put the time and efforts needed to achieve it.