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Old 4th July 2009   #282
hendrikxix
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RT60 absorption coefficients for reflective floors

I don't know if this helps at all, but this is the number set that I use when I am estimating the RT60 for spaces that haven't been built yet using the Sabine RT60 Equation: RT60 = (0.049 for feet)*(Volume of Room/ Sum of all Surface Areas * Their Absorption Coefficients)

It should be noted that this formula is intended for use with rectilinear rooms only, but in practice I have found that it is pretty effective (within 10%) when the actual room is measured later.

Sorry about the word wrap:

Code:
Floors                                                    
Sound-Reflecting            125    250    500    1K    2K    4K                                        
                                                    
28. Concrete or terrazzo        0.01    0.01    0.02    0.02    0.02    0.02    
29. Linoleum on concrete        0.02    0.03    0.03    0.03    0.03    0.02    
30. Marble or glazed tile        0.01    0.01    0.01    0.01    0.02    0.02    
31. Wood                0.15    0.11    0.1    0.07    0.06    0.07    
32. Wood parquet on concrete        0.04    0.04    0.07    0.06    0.06    0.07
The data comes from a variety of sources, mostly acoustics reference books. I suspect that the wood parquet on concrete is probably the closest to wood floor on parquet that I have. The data is an absorption coefficient with 0 being perfectly reflective and 1 being completely absorptive. It looks like wood parquet on concrete and concrete are pretty close in the grand scheme of things. Painted poured concrete walls, I suspect would be similar to stained poured concrete floors assuming the stain seals the air holes.

BTW as far as the ceilings go:
Taller ceilings that are bumpy and irregular are usually pretty nice sounding, similar to the reverb cap on recital and concrete halls. Concave shapes focus and amplify, while convex shapes tend to diffuse sound.
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