"IRCAM (the Institut de Recherche et Coordination Acoustique/Musique) is now using a Macintosh to manipulate the acoustic properties of its main performance hall, the Espace de Projections (ESPRO). The walls and ceiling of ESPRO have 171 three-part panels, each of which may be adjusted to exhibit one of three acoustic properties: reflection (the sound is reflected along a single plane), diffusion (the sound is reflected from a three-surface prism at different angles), and absorption (sound is not reflected). Three mixed positions, such as absorption/reflection, are also available. Furthermore, the ceiling is divided into three parts, which may be raised and lowered independently. All of this provides control of the inherent acoustic properties of the room, such as volume and resonance. The ESPRO can even be tuned to reinforce a specific musical key.

IRCAM’s Adrian Freed and Mark Seiden have developed Automatisation de Periactes, a Macintosh program designed to control the acoustics of the ESPRO performance space.

The user literally paints (with patterns similar to MacPaint’s) the acoustical properties of the walls on the Macintosh screen, which presents a two-dimensional view of the room’s four walls and ceiling. Motors move the actual panels to the positions that provide the reflection, diffusion, absorption, or mixed properties painted on the screen—real-time interaction is also supported.

The acoustic modeling of the panel configurations may have taken up to two days of dedicated VAX computation time to derive. The resulting design, exhibiting the desired acoustical properties, can be saved and recalled instantly. Well, almost instantly; the panels take about ten minutes to move, and although their settings are saved in the file, the lowest row of panels cannot be moved automatically. Anyone standing in front of one of the 75 non-motorized panels could be injured when it moved.

This is truly the largest Macintosh peripheral in the world."

—Christopher Yavelow

IRCAM's ESPRO is truly a unique and unusual space in the world and was extremely technically challenging to build and outfit. It has constantly required expensive maintenance - most recently a complete remodeling with the addition of digital virtual acoustics. After the first decade of use the huge custom console to configure the panels broke and nobody presented affordable bids to fix it. Mark Seiden and I proposed a different solution: replace it with an Apple Macintosh and software to bypass the physical controls on the console and talk directly to the machine control hardware that moved the huge array of heavy panels. IRCAM accepted our bid and we implemented the software between memorable visits to Paris restaurants. Dividing the work was easy - I did the UI and Mark did the machine control bridge.

For reasons I don't remember we both retained copyright on our respective code - it's odd because little if any of this code could be reused on another project. This makes it uncomplicated for me to create and publish the demo below which is my friend Claude's reinterpretation in JS of my original C language code with a rough approximation of the black and white tiny screen of the original Mac Plus this ran on. I have added some modern conveniences you can choose on the left which reflect what might have happened if IRCAM had asked us to maintain it. (It is a remarkable milestone to experience with AI programming that I never reread my original code or any code Claude synthesized to get this going - it was all natural language discussion of the specification of the user experience I wanted to provide.)

At some point IRCAM did reimplement in Max/MSP providing a UI that closely resembles what we originally did. I am indebted to Chris Yavelow who took the trouble to write that article for MacWorld and entertained us with many interesting stories during our brief time in Paris together. Mark took the picture for that article.

The real gift of this project was to experience a creative project at IRCAM free of the well-documented politics I had experienced two years before and of course the company of Mark - whose enthusiasm for many things that Paris readily provided was infectious: great music, great company and great food. A lunch Au Pied de Cochon was particularly memorable because we were there when the kitchen caught fire and the fire brigade rushed in with axes and hosepipes at the ready.

Here are more stories of my adventures in the ESPRO.