I have been observing these phenomena for years and I have no explanation for it. Not that I requires any explaining, BTW…

Pretend that you have a stereo installation where right and left channels produce absolutely symmetrical acoustic output. A slow mono 20-20K frequency sweep holds the center Mono Point dead stable with no, even insignificant, fluctuations horizontally or vertically. It is not how most of acoustic systems in room, including my Macondo are functioning,  but I am talking about a hypothetical perfectly symmetrically-imaging installation.

Now let play stereo music and get a certain imaging, or in this case it would probably be better to talk about not imaging but about what they call “soundstage”. So, we got a specific “soundstage mapping” and the specific phantom sources positioning. Let record this positioning in our memory and particularly distances and angle.

Now, let flip the right and left channels and to listen what we got then. Considering that our right and left channels are absolutely symmetric, even in context of the given room acoustic, we might presume that the “soundstage mapping” would be perfectly reversed but symmetric. The specific angles and the specific depth excursion that use to be on right must be now on left, correct? Yes it will be but ONLY with test tones or with simple music, even chamber music….

Playing however a real orchestral material the effect of symmetry will NEVER happen!

I was not able to found any audio explanation and I think it has more to do with our perception of orchestra pre-discriminated. Listen an orchestra with first violins on right and second on left and you will see that no matter how good orchestra played it sounds “internally destroyed” and uncomfortable. I have no idea why and have no true explanation to the phenomena. I would like to have an opportunity to hear a well-performing orchestra “live” with reversed positioning. There was a few times when I have a change to listen “live” orchestra sitting back to it. I did not redetect any discomfort but I did not get positive feelings as well.

So, I wonder if a positioning of the instruments has been pre-engraved in out subconscious?

I would say that this is probably related to the human emphasis on horizontal differentiation.

Much of what we see is influenced by our evolutionary skills of pattern recognition.

If you take a photograph of your mother and reverse/flip it in the horizontal axis it can be quite surprising how unfamiliar it can look.

Take a stereo recording, any stereo recording and listen for 1 hour to the same short piece of music. Then flip the L/R channels and listen again. In most cases, this will be perceived as an instant catastrophic reduction of sound quality.

For further interest, take the same recording, now flipped in L/R and listen for a further 1 hour, until you become used to the sound and then flip it back again. Another catastrophic reduction in sound quality.

It is a great trick to play in the studio after 3 days of recording & mixing.

Andy