The future: another scale of feedback?

Artist statement by Mario van Horrik and Petra Dubach
Mario van Horrik (Eindhoven, NL, 1956) is a sound artist. Since 1982 a member of the Maciunas Ensemble, an experimental music group with Paul Panhuijsen, Jan van Riet and Leon van Noorden.

From 1983 collaboration with Petra Dubach (choreographer, dancer, performance artist); concerts, in situ works, performances, installations, works in progress, objects, graphic works. Presentation of works a.o in New York, Boston, Cleveland, Vladivostok, Istanbul, Brisbane, Bamako (Mali), Kaliningrad, Bilbao, Moscow, Zurich, Munich, Jekaterinenburg, Berlin, Cologne. Music and video published on Bandcamp and Vimeo
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Since the late '80s, my wife Petra Dubach and I have been interested in working with feedback. Petra being a dancer and me a musician, our work evolved into the concept that sound and movement are identical: if nothing moves there is no sound.

Through the years we have developed performances, objects and installations based upon different types of feedback, such as industrial feedback (measure and control), direct feedback of sound (sound source and speaker are physically connected) and indirect feedback of sound (feedback is generated through the air, like a microphone feeding back).

In 2010 we came across bass shakers. Used in cinemas they are mounted under the chairs and reproduce sounds from the movie in the form of vibrations, so you have the feeling like you are driving a fast car or holding a machine gun. With these shakers we have set up our project called WAVES that investigates the artistic possibilities of movement feedback or vibration feedback.

WAVES resulted (and still does) in numerous concerts, performances, installations and interactive presentations worldwide. Acoustic feedback, double feedback, interactive feedback and underwater feedback were part of our research, often using strings, metal plates, guitars and cymbals as basic materials, besides of course the bass shakers and other audio equipment.


We are no scientists, just curious artists. We move through the WAVES project in our own way and it gives us an immense richness. Not being able and not wanting to be able to explain the wonders we experience from our research is the essence of this richness. Petra and I have chosen not wanting to know everything; this is our method and driving force to continue the project.

We as the human collective are unable to make these decisions. We all go with the flow, as the saying goes.

The work with feedback (only a very small part of the entire global range of interests and activities) allows us to step outside this global flow and we’ve come to the conclusion that slowing down to near stasis and taking very much time for one thing at a time is another factor that contributes to our feeling of being rich.


Gradual Process WAVES.

In 2020 we made a very strange discovery. Up to then, we believed that changes in the sounds of a WAVES setup using direct feedback could only be caused by materials or objects that are ‘transported’ by the vibrations of a string or a metal plate or such. An object like a curtain hook hanging from a vibrating string can be forced to move forward or backward by the vibrations in the string. This of course causes changes in the vibrations and the sounds. It may lead to changes in the sound colour, beats, or volume. It may also lead to silence or destruction of equipment and/or ears.

The video shows a spring that is clamped on a long string. We were not surprised by the fact that a spring can be set into a repeating motion, given the nodes and antinodes in the string. It was not our intention to create this pendulum. Before, we had noticed the same swinging movements when we had clothes pins clamped to a string, but it never had the sonic effect that the spring has.

We cannot explain why these slowly changing patterns are being generated by the system. They are reminiscent of some ’60s and '70s gradual process music compositions and can have a very hypnotic effect. On our Bandcamp site we published a digital cd with 4 gradual process WAVES recordings:

It is always by coincidence that we manage to clamp a spring in such a way that it is going to swing and create these patterns. The slightest change in position can, and often does disturb this phenomenon. We gave up trying to find a system that would make it easy for us to have springs swing.

Interactive feedback.

Church WAVES Interactive performance.

In the (out of use) Church of the Holy Heart in our home town Eindhoven we tensioned two long strings, each 50 meters long. Each string has on one end a piezo transducer and on the other end a bass shaker. The piezos go directly into a guitar amplifier/speaker. On the altar, a wireless mike is placed. The signal of the mike goes into a mixing board and the output of the mixing board goes into a HiFi amplifier. The loudspeaker outputs from the HiFi amp feed the shakers. All the volumes are set so that the whole system produces feedback sounds. So it is an indirect interactive feedback system.

It is obvious that there is a relationship between the slow movements of Petra and the changes in the sounds.

For us, it is enough to know that the relationship is there and that such a setup allows us to make performances that are interactive with the feedback system. That doesn’t mean that we don’t take into account other parameters that are decisive with regard to the result: the architecture of the building and its measures (the altar as an acoustic significant position), the length of the strings measured by the position of the pillars in the building, the materials and tension of the strings and the positioning and direction of the speakers of the guitar amp/speakers, and the volume settings.

It is too complicated (for us) to combine all these facts and numbers into a kind of formula that would be valid under all circumstances. So a lot of the process is trial and error; some is using the knowledge that is already in the building, and some is the experience from other feedback researches.

Besides the setup of materials, there is a second feedback system that ‘steers’ the first one, or ‘plays’ with it. This second feedback system is Petra who moves slowly. Her body influences the sound waves in the building and moving her body changes these influences. She has experienced already that a slow tempo is best; that sometimes she has to wait, that she can repeat movements to create patterns. But she also listens to check where her influence starts and where it ends; to check which tempo is best, when to stop and when to continue. She has to find out where her influence begins and where it ends, not only spatial but also mental. Measure and control.

It’s like a duet between two musicians, each giving input and responding to each other’s input; creating a piece of sounds together. It is also an investigation into the positioning of a body: sometimes the relatively small body of Petra in this huge church can influence the atmosphere in the building just by lifting an arm or changing weight from one leg to another.

The position of the video camera was fixed during the shooting, and my position as the cameraman was fixed as well. We took some time before the shooting to find the best place for the camera. And that brings us to the third feedback system that is not on the video, but easy to imagine: the situation of a live performance in front of an audience. Other people in the space would have an influence on the sounding results and on Petra’s position, her movements and the sounds. A sitting audience would have been different from a standing, moving audience. The latter would have made the performance and its sounding results possibly more dynamic and would have made Petra’s performance even more ‘difficult’.

If we would have been allowed to have audience in the church, we could have presented it as an interactive installation. The movements of the people in the church would have been responsible for the development of the sounds and they would have been the musicians or choreographers. Some or maybe even most of them probably wouldn’t be aware of this.

It didn’t happen; it will only happen when we’re given this opportunity sometime in the future. But it’s a very nice fantasy, not unrealistic and very much fitting our methods and concepts.

A selection of sound recordings and video’s from the church has been published by Edition Telemark from Berlin as an LP and DVD:

Interactive Feedback on another level.

The COVID19 pandemic has changed our world. For us, as for many, it has decreased the possibilities to travel the world to present our work. A good opportunity to reconsider the possibilities. Aside from the obvious advantages (less traffic, more work at home, less pollution) another vision on the production, the distribution and the sharing of products might contribute to another ‘world order’.

Our first steps towards a new approach of art production, sharing and consuming: WAVES Guest.

Neologicka synagoga zilina

The WAVES “Sphere” project. (1st WAVES Guest project).

WAVES installation, Sphera, Nova Synagoga, Zilina, Slovakia

In 2020 the artist Juraj Gábor (1985, Slovakia)started the “Completing the Sphere” project in the beautiful space of the New Synagogue in Zilina, Slovakia , in close collaboration with the organisation Truc Sphérique.

Photo Jan Kekeli for 20 Banska Stanica 2101

Juraj exhibits large scale installations, often made of wood.

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For the synagogue he is mirroring the dome (the “hemisphere”) of the roof, creating a sphere in every sense.

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Sphere under construction. 

The sphere is 17 meters in diameter and one of its purposes is for other artists to use it as a stage, a playground or as an inspiration for other works.

So far many artists have presented works in the Sphere including visual artists, performance artists, sound artists and musicians.

On May 27 2020 we did an interview and live stream concert for the Nova Synagoga

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The original plan was that we would come to Zilina to play a live concert, but due to COVID-19 this was impossible.

Sometime after the concert, Kamil Mihalov of Nova Synagoga asked us if we would be interested to come to Zilina for a short residency and to use the time to set up a WAVES installation inside the Sphere.

Of course we would like to make a contribution to this very nice project, but with the virus still around it looked as if our physical presence in Zilina was uncertain. In February 2021we had a zoom meeting where we discussed the options and we suggested the possibility of having the WAVES installation installed “from a distance”. Kamil and Juraj were to provide the hardware needed and technician Andrej Hinka assisted in the construction of the work. Then Kamil and Juraj would spend time with the installation in connection with us (Zoom live or video recorded) to find the most optimum tuning, preparation and settings of the audio equipment and the long strings.

The challenge.

We have 10 years of experience in working with the WAVES concept and this would be a radical new phase in the project.

In our opinion, the WAVES concept is very solid and it should be possible to set it up and work with it for other (selected and passionate) people. But is this true?

In the 10 years of research, we have experienced that it is not a good idea to have too many expectations on the results of WAVES. The more you let the setup do its own “thing”; the ‘better’ it is.

So one of the aspects of the WAVES project is to give more space to the work and less to the artist.

Now we’re going a step further, by giving other people the opportunity to play with a given setup and make choices towards the (temporary) result.


We have been thinking about the materials needed; the hardware setup, the fine-tuning and the documentation of the result(s).

Materials: some materials needed are obvious: bass shakers, strings, piezo pickups, cables, amplification etc. These are all in a list, with links to suppliers for some of the more specialist materials. The more common building materials, like rope and turnbuckles are probably available at most local hardware stores.

Other materials, like the preparation materials (the small objects clipped to, hanging from or attached to the string) are to be chosen by the people who are going to play with the setup.

Instructions for tensing the string(s) and connecting the audio equipment are all communicated through short videos, descriptions and schematic drawings.

A simple setup using only one short string should be made in order to check if everything is connected well and working properly.

Installation: Before installing the hardware, we should decide what function the work should have: if other artists are to make use of the WAVES installation it is possible to have it installed as an interactive installation, where the position and movement of performers influence the sounds of the WAVES installation. It is also possible to have the work ‘driven’ by external influences, like a microphone picking up street noise. But of course, it can also be an entity of its own, responding to the acoustic qualities of the sphere itself.

Once this decision has been made, the position of the work within the sphere has to be determined.

It is essential that the audience is unable to touch the work. Cables should also be out of reach of the public and all equipment should be placed where it’s only accessible to authorized people.

Next, the technical staff can set up the string, shaker, turnbuckle construction and put the string under tension as instructed. The necessary cabling can be cut in the desired length and welded.

It’s best to keep the distance between the piëzo and the mixing board as short as possible.

This all done, the technical staff and the ‘player(s)’ together check if the construction is set up well and if the players are able to prepare the string(s) over their full length. Also, if needed they need to be instructed by the technical staff on how to switch the installation on and off and informed about the function of each piece of equipment.

The players. The most important capacity of a player is that he or she has a passion and fascination for the kind of sounds that are produced by the WAVES installations and has ‘good ears’. They also need to have much time, be very patient and able to work precisely. An open mind and no expectations are essential as well. On the other hand, they can make decisions on the final result(s) completely to their own taste. So there is a lot of restriction and freedom at the same time.

The players start with experimenting with the positions of the piezo, their amplification, the settings of the equipment and the sound volumes, to get acquainted with the materials. Also, they should experiment with a fixed setting of the amplification. Making small changes in the position of the piezo can have quite some effects on the sounds, so the players should become very much aware of this by experimenting with this.

Finally, the players choose the preparation material and experiment with that. There also, positions can make a lot of difference. When there is a setup completely to their satisfaction they should check if a comparable result is achieved when turning off and then on the equipment again.

And so Kamil and Juraj took the time to work with the installation.

In the summer of 2021 WAVES was installed and presented to the public within the Sphere installation. Given the construction of the Sphere it was very difficult to really ‘play’ with it.

So Juraj and Kamil decided to choose for two strings with a fixed position without the preparations. They were really excited when the first sounds were generated by the system.

They were also very surprised to notice that the sounds were different all the time. Most probably temperature and draught played a role in this and maybe minimal changes in the positions of the piezo pickups under the influence of the vibrations of the strings.

The reactions of the public were mostly very positive. Many people spent time lying in the Sphere listening to the sounds.


It is obvious that this new approach (WAVES Guest) has many new possibilities.

We are proposing a change in mindset with respect to art: how can art be made and how to consume art are (in this concept) no longer different disciplines. A curator can be the artist and will be the consumer in one.

The consumer can be the creator or interpreter in one. Borders are disappearing; feedback takes over every ‘level’ of the process of the creation of a WAVES Guest work.


31 January 2022
Review status
Editorial review
Cite as
van Horrik, Mario, and Petra Dubach. 2022. "The future: another scale of feedback?" ECHO, a journal of music, thought and technology 3. doi: 10.47041/TJLH4675

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