A crucial point here is, in my eyes, indeed the question of what one "has learned to observe/to ignore". Several decades into the history of sound art, I feel the medium is still quite marginalised in contrast to the dominant visual culture. I am still often surprised at the indifference of people to sound, or more precisely, an indifference of the aesthetics of sound - of course, people discern noise, speech, music, but all in neat categories and nothing in-between; this is perpetuated by a culture that employs sounds and "music" in very stereotypical ways. And I think, the "political" dimension of sound work often lies in this very basic programme of providing ways of learning to observe sound, tiny sounds, subtle sounds, sounds that refuse to fall into categories, etc.
The image of "Doppelgänger" is very interesting to me. It's exactly about the margin between same and different - this Cooper, the other Cooper - and I have worked several times with differential processes based on similarity, so you imitate something, or an algorithm imitates something, but an element of error or transformation is introduced, voluntarily or involuntarily, that serves as a generator of trajectories. More precisely, Doppelgänger denotes something that is phenotypically the same, but genotypically different.
How do margins manifest themselves? I can see two principle forms. The first is the gradual change, something that you employed in The Weather… Actually it's a double gradual change - one that is with respect to any visitor passing by, as a function of time, the other being respect to the same visitor passing by repeatedly on different days. It reminds me of a piece I did in a former prison, Zelle 148 (2006), although this is inside a dedicated exhibition space, and the visitor has to put on headphones, so the situation is quite different from an encounter in public space in a "state of distraction". Nevertheless, it reminds me. The piece is re-triggered as the visitor puts on the headphones which are mounted so that one has to sit in a very particular spot on a plank bed. The headphones are closed, but one hears the acoustics of the space which had been recorded in the same position, giving the illusion of open headphones. Then after a while, a sound is introduced, a heavy stone that is being dragged across the floor of the prison cell, emphasising the acoustic illusion, as it is seemlessly resolved inside the acoustic of the space.
I don't know if this counts as a gradual change, though. Another example would be a live performance I did once with my friend Ludger Hennig inside an old forge. I don't remember which way the transition went - from real space to virtual space or vice versa - but we were using the fan belt of the forge to start (or end?) the piece, a fantastic sound that goes all across the old building, and we slowly transitioned to or from that sound to recordings thereof, transitioned to or from the multiple speakers installed in the space.
I want to contrast this gradual change with a more abrupt change that marks the margin by going discontinuously from the Doppelgänger side to the other side. This is most effective in the "negative" direction, for example taking away the "Doppelgänger". In the piece Sliding (2013), I installed sound on two indirect speakers hidden in the ceiling of the entrance of Graz's local state broadcasting studio (ORF). That entrance is particular in that it is only a short - few seconds - transition between the outside, located in a green park, and the inner rondel that connects to the studios and offices. The entrance opens to both sides using sliding doors, and I wanted to portray that ambiguity between outside and inside by simply playing back, alternatingly, recordings from the outside and from the inside. Both recordings are "credible" or "plausible" in that when you pay attention to the sound in the space, not much indicates that the sound is artificially installed (of course, if you pay attention, you realise that the acoustics can't match). Then in short intervals, so with a slight chance that someone passing by intersects with them, the sound is abruptly stopped, revealing the mark made.
Another useful term may be "irritation", which I guess is the moment where we move from plausible to implausible and passing the margin of "something bothering us", or something "not fitting". I wonder, how we can move this discussion towards questions of algorithmicity. One strand, perhaps, is the transparent interface in Mark Weiser's concept of ubiquity. Intuitively, we want to introduce an opacification, we want the algorithms to become bothering in some way. Is this an inherent potentiality of algorithms, or something we bring to it from the outside? Or are algorithms turbid by default, and transparency is just the ideological program of "design" and "engineering"? Another question is, if algorithms are particularly useful to play with the transition between plausible and implausible?