| The key to whether the results are meaningful is the shape of the Schroeder integral. In a large room with a well diffused soundfield the sound decays logarithmically, which means a plot of the level in dB against time is a straight line. The measures of RT60 are built on this assumption of a log decay, and they tell us the slope of that decay line in seconds per 60dB. In small rooms, however, the soundfield is often dominated by specular reflections and the decay no longer follows a log trend. Best-fit straight lines to the Schroeder curve can still be derived, of course, you can put a best fit line through any data, but the answer becomes of little value. A measure of how well the data is following the line is the correlation coefficient, REW flags as suspect values with a correlation coefficient worse than -0.99 - the values are shown in italics in the cursor field. Other software will doubtless treat that differently, and choose their own thresholds, hence the "0" values you mentioned.
The big increase in response uniformity in Ethan's results look to have come when a lot of diffusion was added to the room, which would make sense, but we'll have to wait for the video to see just how extensive the treatment was.
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REW Author
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