September 9, 2013 § 4 Comments
Last in the series of new sound art works commissioned by the RESONANCE Network in the 2012-2014 period is Photophon, an installation by the Belgian artist Aernoudt Jacobs. As small and fragile as it laborious, Photophon will premiere as part of the RESONANCE-in-Maastricht showcase that is taking place between September 13th and 29th at Intro in situ’s. (The exhibition in Maastricht will also include a new installment of Signe Lidén’s Writings and another presentation of The Beaters by Thomas Rutgers and Jitske Blom. Peter Bogers will present a second version of his Untamed Choir and David Helbich made an arrangement of the performative soundwalk that he composed for the Flanders Festival in Kortrijk, for the streets and squares of Maastricht.)
Photophon is based upon the so-called photoacoustic effect, that was discovered in the late nineteenth century by the brilliant Scottish scientist, inventor and innovator Alexander Graham Bell, who probably is best known as the inventor of the telephone. As a teenager Alexander Bell witnessed how his mother slowly grew deaf, which aroused his very special interest in all things related to speech, hearing and sound. In 1880, together with his assistant Charles Tainter, he developed a device that transmitted sounds wirelessly, on a beam of light: the photophone. It reflected sunlight from a flexible flat mirror that actually served as a microphone. When somebody talked against the mirror’s back, the variations in air pressure caused by the soundwaves of the voice moved the flexible material, and were literally reflected in variations of the brightness of the mirrored sunlight. One then ‘only’ needed to translate these back into sound…
It was while working on this receiving end of his photophone that Bell discovered the optoacoustic or photoacoustic effect. He found that solid materials that were exposed to a beam of sunlight that was interrupted by a fast turning wheel with slots (thus giving rise to a very rapid series of light pulses), started to produce sounds. The main (though not sole) reason for this is photothermal. The physical explanation goes roughly like this: the material is heated by the light energy that it absorbs, which causes it to contract and expand; these ‘movements’ of the material then give rise to pressure changes in the surrounding air; but that of course means that there will be sound!
It was this use of strictly ephemeral phenomena to create sonic events that inspired Aernoudt’s artistic re-interpretation and development of Bell’s discovery. “I was mesmerized by the idea,” he says, “that sounds around us can be created with light. From Bell’s research notes I learned that any material comes with a sonority that will be revealed by hitting it with a strong enough beam of light. Every material has a resonant frequency, but every material can also be ‘sonically activated’. And its sound is directly related to its resonant frequencies. For me this was a revelation, touching the world of sounds in its very essence!”
Aernoudt’s work is a fine example of a combination of artistic and scientific research. He has been developing his Photophon installation in close collaboration with the Laboratory of Acoustics and Thermal Physics of the Catholic University of Leuven in Belgium. I saw a prototype (picture above) of the elegant and intriguing horn-like object that is to become the sounding heart of the installation, when earlier this year, at the IMAL in Brussels, I visited an exhibition of Overtoon, the Brussels based platform for research, production and distribution of sound and media art that is directed by Aernoudt and Christoph de Boeck.
“The horn is the last in the chain of elements that together make up the photophonic object that I imagined,” Aernoudt explained. “It acts as a loudspeaker. Because of its specific dimensions, it will amplify some of the frequencies produced by the photoacoustic cell that I built. That cell is a kind of Helmholtz resonator, placed at the narrow end of the horn. Eventually, the horns will be between 60 and 70 centimeters long, very narrow at the one end (about 3 millimeters), and then widening to some 22 centimeters at the other end. The precise dimensions are related to the resonance frequency that I work with.”
“In the very first version I used the horn of an old gramophone that I bought on a flea market. The light source was a green laser. That Photophon produced a soft buzzing sound. The subsequent versions use customized horns, that are adapted to the cell. All is centered on one specific frequency, with its corresponding over- and undertones. I started with a plastic horn, realized in one piece using a 3D printer. But that was too fragile. It broke rather quickly. The model at the IMAL exhibition also has a plastic horn made with a 3D printer, but that was done in 3 separate parts, that I then glued together.”
At the IMAL I saw light, I saw movement, but I did not hear any sounds.
“True. But that’s because the light source was a led, which is not intense enough to produce a sound that is audible with your bare ears. There is a sound, but you would need to use a stethoscope to hear it. With a laser source, that I can use in my studio, the sound becomes audible. So for the RESONANCE installation in Maastricht, I will use laser sources.”
And you will use glass horns. Glass surely has acoustic properties that are quite different from those of the plastic you used for the earlier versions. This will also influence the sound, I presume.
“Yes, it will influence the sound. The glass will resonate more than the plastic. And of course there is the visual, the aesthetic aspect. The transparent glass horns will make for a far more delicate look than that of the the opaque white plastic objects.”
How did your collaboration with the Laboratory of Acoustics and Thermal Physics at the KUL, the Catholic University in Leuven, come about?
“We have been working together for about one year and a half now. Our collaboration started after I had invited them to come to one of my earlier exhibitions. At the time I already was researching the sonic and acoustic investigations that were done in the 19th century, and the empirical sound theories that were developed at that time by people like Hermann von Helmholtz, Rudolph Koenig, Jules Lissajous, and so on. I was particularly intrigued by the fact that in many cases those investigations were based only on acoustic phenomena, with no electronics involved. They analyzed everything with analog, mechanical devices. It makes their findings very palpable and understandable. Christ Glorieux, who is the head of the Leuven Acoustics Lab, introduced me to Bell’s photophone, that they were working with a lot at the laboratory. And this then gave rise to the idea of making an installation based on the photophone.”
“Art-science collaboration are sort of a trend these days. So my case is surely not unique. It is very interesting though. Also, because it is not always easy to really work together. Unlike a scientist, as an artist I am all the time groping around in the dark. As an artist, that is where you want to be. Where you need to be. You will always want to try out things that are deemed to be ‘impossible’. Putting a horn on a photophone was one of those ‘impossibilities’… The scientists at the lab would never use a horn. They put tiny microphones inside the acoustic cell. Which, from their point of view, is far more manageable. It is what they need for their scientific approach. But still, sometimes there are holes in their research…”
Which then will allow you to jump right in.
“Indeed. And we can talk about it. That makes for very interesting conversations.”
Do you have a scientific background yourself? Or is your scientific knowledge self-taught?
“Most of it is self-taught. But I did study architecture, which introduced me to many different subjects. A lot of technology. But also mathematics and mechanics. So that makes for quite a broad background. Even though I never finished my studies. I failed the fourth year, after which I stopped and decided to concentrate on music and art. But also as a musician and an artist, I never stopped thinking about space.”
What is the role of space in the Photophon installation?
“It is important that the space be as quiet as possible. It also will be important in the sense that it will determine the way in which visitors approach the installation.”
In Maastricht the Photophon installation will be made of three of Arnoudt’s photophonic objects. Each of them will have a laser light source, with the intensity necessary to produce audible sounds. “The continuous laser light is interrupted by two rotating slotted wheels. These wheels are the second element in the construction,” Aernoudt explained. “Each of the wheels is moved by a small electric motor. There are two of them (separated by a distance of about 5 centimeters), in order to provide two distinct modulations of the laser light. If the first wheel is rotating at a very high speed, the sound produced by the photoacoustic cell will be a continuous túúúúúúúúúúúúúúttt. The second wheel is meant to interrupt that continuous sound, so as to produce a kind of rhythm: túúútt – túúútt – túúútt – túúútt – túúútt … The third element of the object, after the laser and the wheels, is the photoacoustic cell that I designed, and which – as I explained before – is based on the idea of a Helmholtz resonator. It is a small sphere, containing a black disc. Because of the series of light pulses that is hitting the disc, the photoacoustic effect will give rise to a sound. Now the shape of the cell, the globe, is important because it will strengthen certain of the frequencies. What you will hear, then is determined by the rotating wheels, and by the properties of the photoacoustic cell. The Helmholtz resonance and the acoustic properties of the glass horn, the fourth and final element in the construction, take care of some form of amplification of the sound.”
I guess it would be possible to add some sort of a controller to the electric motors that drive the wheels, to change the speed of their rotation in real time, and thus vary the resulting sound in real time. You might then play the Photophon like a musical instrument.
“I absolutely intend to provide a certain kind of ‘musicality’. But in the form of an installation, not in the form of a playable instrument. The musicality is latent. It is present, but hidden. The electric motors are driven in real time by a micro controller, which will give variations and rhythms to the tones. And each of the glass horns will actually have slightly different dimensions. Being handmade, it was impossible for the glassblower to make them perfectly identical. I still have to try them out, but I suspect that volume and resonance frequency will be different for each of them.”
So the sounding result will be like a microtonal chord?
“That is difficult to say at this point. A lot will also depend on the precision and the stability of the electric motors that I am going to use. Only if these can be adjusted very precisely will I be able to produce truly microtonal structures. But as things are looking now, that will not yet be the case in Maastricht. I hope, though, to be able to develop the work further in the near future.”
“As I said before and although this may not be immediately apparent: the musical, the compositional element, is very important to me. But I will only be able to fully exploit this in some next phase of the project. I am already planning a sequel for next year, which would be an outdoors installation. It will be based on the use of sunlight, but combined with new technologies that will enable me to track the sun, and then add artificial light as a compensation as soon as the intensity of the sun becomes insufficient. This confrontation of 19th century technologies with the top technology of our times is, of course, already evident in this version of the work: the laser, the drive of the wheels, the cutting of the wheels… All of this is based on very contemporary technologies, that then combine with these pure, non-electric, analog ideas from the 19th century. That’s amazing, I think. It’s a meeting of two very different worlds and two very different times…”
“Phonophon” was produced for RESONANCE by Stichting Intro in situ in Maastricht, the Netherlands, with additional support from the Dutch Province of Limburg.
The work was developed by Aernoudt Jacobs in collaboration with the Laboratorium voor Akoestiek en Thermische Fysica (Laboratory of Acoustics and Thermal Physics) of the Katholieke Universiteit Leuven (Catholic University of Leuven).