Pinot Gallizio used a theremin in his 1958 installation The Cavern of Anti-Matter alongside industrial paintings, hidden from view it was triggered by passing audience members and would have filed the space with an atmospheric droning sound.
Below are correspondence between Pinot Gallizio and Guy Debord regarding the machine:
Alba, June 14, 1957
I bring you the most astounding piece of news from the Laboratory. I introduced a friend of mine to Olmo. He is a nuclear physicist at the University of Turin who Piero knows well: Mr George Cocito, who arranged with Olmo to make a device called the THEREMIN. This device will allow our musician to go ahead with his interesting experiments. And the person concerned will be able to give you more details…
unpublished typewritten page, Fondo Gallizio, GAM Turin
[Paris], Sunday, February 16, 1958
Dearest Pinot, noble and great friend,
2nd) If you can have a second Theremin, that’s fine… But it is not something essential. However, it will be advisable to present this invention of Cocito as a useful instrument for modifying or arranging raw sound material, in the building of atmosphere.
typewritten page, Fondo Gallizio, GAM Turin