Space as a Symphony of Turning Off Sounds

In David Toop's classic book Ocean of Sound – something I cite repeatedly here on BLDGBLOG – we read about a musical performance that, by accident of circumstance, became a process of turning off all sources of noise within a building.

[Image: Felix Hess assembles similar sound machines, next to a photo of an unrelated concert hall].

For an installation of fifty specially made "sound creatures" – little interactive robots "inspired by the communication eco-system of frog choruses," Toop writes – experimental musician Felix Hess insisted that there be no "extraneous sounds" in the concert hall. Hess's miniature sound performance required absolute silence, or else the machines would not function.
Toop then quotes a lengthy description of the creatures' set-up:

We had imagined that the foyer, on an afternoon when nothing was being held there, was extremely tranquil, but not even one of them began to call out in response to any of the others. So first we turned off the air conditioner in the room, and then we turned off the one on the second floor. Then we turned off the refrigerator and the electric cooking equipment in the adjoining cafe, the power of the multi-vision in the foyer, and the power of the vending machine in a space about ten metres away. One by one we took away these continual noises, which together created a kind of drone there... Hess was very interested in this and said things like, "From now on maybe I should do a performance of turning off sounds."

It's amazing to think, of course, that anything could pick up, and even respond to, sounds that subtle; but it's also quite incredible to imagine one's own acoustic awareness of architecture as a process of subtraction.
You could even turn it into a game:

1) You are sitting on a stage, wearing a blind-fold.
2) Every electrical device in the building around you is on.
3) Suddenly, you detect a slight difference, a vague change in sonic pressure somewhere, as if an extremely distant mosquito has been swatted – a spot of silence, as it were, has appeared in the room.
4) "Toaster, fourth floor!" you call out – and you're right. Someone turned off the toaster.
5) You win a trip to France.

In any case, it's easy to imagine Hess and his assistants finding this process much more difficult than they'd imagined. At one point in the afternoon, then, with only hours to go before the doors open, they have to step across the street and turn off the appliances in a nearby high-rise – and then next door, to a block of flats, and then down the road to the neighborhood hospital. Still nothing.
Gradually they go on to turn off the entire world, street by street, city by city, in an ever-expanding ring of total silence.
The world becomes a sonic sculpture from which sources of background sound are constantly removed.
Finally, twenty-five years from now, as the very last radio is unplugged in a distant house in Tanzania, the "sound creatures" sitting with Felix Hess on stage begin singing.