This doesn't apply to the studio so much in my case because I'm a field recordist but is there a list some where of the amount of sound reflection of surfaces (of all kinds) ? I recorded some heavy equipment today and later I realized that part of the reason the sound was as loud as it was is because the machines were surrounded on three sides by three store brick buildings. The made a horseshoe shape with the equipment at the open side. I thought about it as a large parabolic reflector. I was standing in the building directly across from the equipment so I was at the center of the sound, I think. Then I thought about how much lower the sound would have been if it have been a large open area like a field.