Another example of sound art in public space is this sound installation on the Glasgow Green, a place where people used to bring their wet laundry to dry, as they did not have a garden next to their house, up until 1977.
The Drying Green is a sound installation consisting of four poles with speakers on top, playing the sound of washing machines, thus bringing the listener back to the days when the same field would be full of drying clothes.
I was not able to find the names of the creators of this piece of public sound art. If you happen to know, tips are welcome!