I'm going to guess for this one and say (others will say) ANY walls & any positioning. Thus, I fully expect my local IMAX theater to yank all of their speakers from all of their walls and just stick one of these down front under the big screen. Apparently, the audio experience will be just the same- if not better. 😉
Jokes aside: apparently, a key (differentiating) feature of HP is the ability to put it anywhere and it does some kind of optimization process to make it sound as good as it can from that spot. So if it's close to a wall on one side, the audio from that side is going to "know" and be adjusted accordingly. Assuming that works well, that's a GREAT HP feature.
Now, some of us are taking that concept and running with it to imply it's going to shoot Left channel sound to the left and Right channel sound to the right and thus it's stereo, or even more than stereo. Of course, HP doesn't know where it's audience is sitting. So if I'm sitting over by the "left" wall, I'm getting BEAMED by left channel sound while right channel sound is shooting away from me. But that doesn't support the narrative, so it WILL know where it's audience is sitting, not just how close it is to walls.