|
Can’t resist simply making an observation sure to step on everyone’s toes (after all, to do less wouldn’t be fair, would it? ;-)
First, the measurement of RT60s in a small acoustical space at frequencies where a statistically diffuse sound field does NOT exist, is a bit insane. Wrong tool, wrong environment! The very nature of the problem is operator error. RT60 measurements in acoustically large halls where they indeed do exist are not a problem regarding repeatability.
As far as small room measurements, a great deal of variability is to be expected! If for no other reason than: the methods being used to excite the room, the placement of, and the type of the mic(s) used, the fundamental nature of the measurement type itself, operator presence in the room during measurement and the interaction WITHIN a non-uniform energy distribution.
...Not to mention that if anyone is suggesting the averaging of measurements, this assumes the variability in such factors and fields (as well as the presence of other destructive stimuli - as a source of error or even mistakes...) – which sort of begs the question of the variability of small room sound fields which are by definition variable!!
But as far as the repeatability of measurements made with invariant stimulus, room conditions and measurement technique, and having the results vary in any way outside of a natural probability/error factor, something is amiss with the measurement apparatus, methodology, operation, or some combination of the various factors. And I would suggest that much of this would also point to the need for a more robust measurement methodology, platform and procedure.
As far as problems with diffusion and absorption measurements, wait for Ron Sauros' forthcoming paper on the matter. He blows this issue out of the water.
OK, you guys can go back to beating up on the proverbial horse and each other…;-)
|