[Frank Kruse]

Well we all know that the physical dimensions of a space are at work here. Within the dimensions, of course, we find direct sound and two type of reflcetive sound; early and late. Listeners in smaller spaces are subject to far more direct and early reflective sounds at a higher rate arrival than in a larger space correct? Therefore the reverberant levels are much higher and may even be additive depending on the frequencies in play.

Yes, but wouldn´t the SPL-meter you allign both rooms with "hear" the sum of all those early and late reflections the same way in both rooms and therefore would give you an according reading? I think every thing you mentioned is also "heard" by the SPL-meter. hm...

I agree that the key to the problem is that an SPL-meter c-weighted slow doesn´t "hear" volume the way a human would therefore they are only able to achieve comparable results in comparable accoustic enviroments.

I have a stack of old-school "Tonmeister-books" but I haven´t found articles about roomsize and felt loudness.

Because abviously we are not able to measure the difference with the methods we use every day.

frank.