I think were talking about times much smaller than it take for the sound waves to get to a wall and back to an observer, vs direct to obsever unless you're in a very small room.

Pete, if A is 440, the just intonation C is 264, C-B = 264,297,330,352,396,440,495- 2C=528

The fact that chords sound ok on a piano (12TET) means that the ear finds anything close quite acceptable. It's very forgiving of small errors (and they are % errors because of the logarithmic scale)