Edwin van der Heide / Marnix de Nijs
Spatial Sounds is a purely interactive installation. It's constantly scanning the space for visitors to communicate with.
Spatial Sounds contains two sensors: One Polaroid ultrasonic distance measurement sensor with self developed software and hardware based on a microcontroller. It generates midi output. The sensor is mounted on top of the speaker. It measures the distance of objects in front of the speaker up to 7 meters.
One biphase angle measurement sensor with self developed software and hardware based on a microcontroller. It generates midi output. The sensor is mounted on the bottom of the axis. It outputs the current position of the arm in steps of 3 degrees. The information of the sensors is communicated via midi to a Macintosh computer. The computer runs self developed interaction software created within MAX/MSP. The software generates the sound in real-time. The software controls a triphase motorcontroller via a midi to voltage converter. The motorcontroller controls the speed and the direction of the motor. The software controls a lightdesk to change the light settings and incidentally switch on a stroboscope.
It's essential for Spatial Sounds to be able to distinguish the visitors in the space from the space itself. Every time the installation is set up in a new space, the installation first has to learn the shape of the space. This is done in the following way:
The installation spins slowly in the empty space. For every possible angle the arm can make, the actual measured distance is stored in a table. The result in the table will be a two-dimensional map of the walls (and other objects) in the space.
After the table has been stored, the installation will be able to recognize the visitor because at the place the person is standing the measured distance will be shorter then the measured distance to the wall in the table. The current distance measurement is always compared to the measurement stored in the table for that particular angle.
The interaction of Spatial Sounds is continuously changing. When there are no people in the space, it becomes very quite in terms of both movement and sound. The arm slowly spins in one direction waiting for people to enter. The installation shows that it detects the visitor(s) by playing a soft sub-low sound. The installation wants to be sure that the visitor is staying and waits until it detects it/them again. Then it starts to become more active. It reacts very directly with a strong sound when it faces the visitor. The timbre of the sound depends on the distance the person has to the speaker. The visitor is invited to become a participant. The movement of the installation is fully based on where people stand. The installation can follow and/or swing around the participant. It can also deal with multiple people. When there are multiple people, they can really interact together. The installation produces a stronger continuous sound as well. This sound is directly related to the speed of the arm. The angle sensor is used to calculate the speed.
The sound itself is not preprogrammed, only the control of the sound and the way the sound is generated is programmed. In this way, the sound generation is directly linked to the physical properties of the installation. The software has a memory for where it has recognized people. If people are not very active (if they stay in the same place all the time), the installation will start to ignore them after a certain period. The more you play with the installation, the more active it becomes. However, the installation can get out of control or overexcited. It will stop swinging and following people and speed up very fast. The sound becomes loud and is related to both the people it recognizes and the shape of the space. The surrounding of the installation is the 'score' for how it sounds. Since it is spinning continuously, it will start to generate rhythmical patterns depending on the shape of the space and depending on where people stand in the space. When people stand close to the installation, it will spin very fast. When people get scared and take more distance, the speed will decrease.
In principle, the installation gets a push from every person in the room. The closer you stand to the installation, the stronger the push is when it passes you, and therefore it will spin faster. This out-of-control period can vary between a couple of seconds and a bit more than a minute, depending on how close people are standing to the installation. Then it will gradually calm down again. People will be able to really interact with it again and its behaviour changes again from there.
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