directional sound

May I Have Your attention, Please, originally uploaded by

I am doing a series of projects called soundpockets for urban interface oslo, which in different ways tries to create pockets of sound in public space. Some of the versions involve the fm sender- mp3 setup mentioned in the previous post, another one involves a directional speaker mounted on a pan/tilt unit, and this has been my second headache this summer, finding a controllable pan/tilt unit which is reasonably fast, which can handle a load of a few kilos and which is not ridiculously expensive.

Fortunately I have had good help from Soundscape studios. The first ideas was to use a existing movinghead light and refit it with the speaker, but it turned out that the motors wouldnt be able to handle the load. Pan tilt units are usually made for a specific purpose, either light or video, and the few ones which are available for general purpose use and which are controllable are very expensive.
The one we have ended up with is quite expensive, but is controlled using serial protocol, is made for outdoor use, and is powerful enough to handle video projectors (for later projects). It is also very fast, up to 300 degrees per second pan, and 60 degrees per second tilt. Hopefully it arrives next week.

The most ambitious plan is to control it using an arduino microcontroller, which will also control a serial-controllable mp3 player, the daisy, so I should be able to place sounds quite accurately in a space, and also create movements with sounds.
If time runs short I will use a macmini with max controlling the sound and pan-tilt unit over the serial port.

I have been testing two different models of directional speakers which uses ultrasound as the carrier signal, I will probably have to go for the smaller one, although I am a bit worried it will disappear in the ambient sound. It is also challenging to find the sounds which works best, and also how to deal with the sounds both coming directly from the narrow beam of the speaker but also the reflections on surfaces in the space.

The inspiration for this projects comes from when I studied in Trondheim in the 90ies, and I heard some stories about how a directional speaker had been used to cause a certain distress on a bridge over the local river: A person walking alone across the bridge suddenly hearing whispering voices. An out of tune clarinet projected into a marching band playing on the 17th of may (Norway´s national holiday).
If these stories are true or not, doesn´t really matter, it is the idea of having a private experience in a public space which intrigued me.

One Response to “directional sound”

  1. Soundpocket 1: disturbing the soundscape « Conversations with spaces Says:

    […] a directional soundbeam to project a localized sound into a public space, this sound being only heard by the people within […]

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