In the second post of the series he says in passing:
My initial setup for recording was flipped 180 degrees from last week, with my bell facing directly towards the door and front wall of my office. After trying a few takes with this setup, I wasn’t very happy with my sound, and I also was having more trouble than usual with fracking notes. The notes seemed to be splitting in an unusual way, and I think this was in part because of “slap echo,” a type of harsh echo effect which Derek Wright discusses in this excellent post on making an audition tape. Make of this what you will, but after slightly turning so that my bell wasn’t directly pointed at bare surfaces, the recording went much more smoothly.
In the comments I asked:
Are you saying the angle of the bell had an indirect effect on your playing? I can believe it, just want to be sure I’m understanding you. Is it that the bad acoustics interfered with your auditory feedback? Or is it possible the sound waves in the room actually interfered with what was happening in the horn?
In this case, I think it was the latter of the two. I believe the actual reflection of the sound from the back wall was causing some additional accuracy problems for me. The sound wasn’t great either, and so I’d be willing to bet that both the inaccuracy and weird sound were caused by playing too close to the wall.
If I didn't play the horn I'd have a difficult time believing this. I think he's right, though. No other instrument I've ever played is so greatly affected by the environment in which it's played. In this specific case, I can't imagine the actual mechanics of sound production of any other instrument being as affected by standing waves in a small environment (which is my guess as to what's happening).
Jonathan West's comment is so on point, want to bring it up to post level:
I'm not in the least bit surprised by this. One orchestra I play in, for the concerts we are tightly squeezed into a narrow area at the front of the church. The area is made narrow by the lady chapel on the left and the organ on the right. So the person on the end of the horn line has his bell right up against the wooden panel of the organ casing. It's horrible to play there! But even one seat over is usually OK. It makes life hard for the 2nd & 4th horns
On the other hand, sometimes I practice in my bedroom. There is too much soft furnishing in there and it absorbs the sound to an extent that I just don't feel I am producing any tone at all.
And then there is the traditional problem of the timps being placed just behind the horns. The vibrations coming up the bell and hitting your lips make it it near impossible to play during a loud timpani roll. Often, relatively small adjustments to position can make all the difference, they cause the phase and/or amplitude of the reflected sound to change to the extent that the problem goes away.
In the circumstance described by James Boldin, I'm not in the least bit surprised that turning the seat a little was all the change that was needed to eliminate the bad effect.