Absorption Coefficients

I've taken these figures from different sources, so there's a mixture of metric and imperial measurements. Hope they help.
By the way, typing absorption coefficients out is a pretty boring thing to do…

Material	125Hz	250Hz	500Hz	1kHz	2kHz	4kHz
Plaster on lath	0.14	0.10	0.06	0.05	0.04	0.03
Carpet on concrete	0.05	0.06	0.14	0.37	0.60	0.65
Floor (wood joist)	0.15	0.11	0.10	0.07	0.06	0.07
Painted plaster	0.01	0.01	0.02	0.02	0.02	0.02
Walls (½″ plasterboard)	0.29	0.10	0.05	0.04	0.07	0.09
Windows (float glass)	0.35	0.25	0.18	0.12	0.07	0.04
Wood panelling	0.30	0.25	0.20	0.17	0.15	0.10
Curtains (cotton draped to half area)	0.07	0.31	0.49	0.81	0.66	0.54
Air absorption (per m³ @ 20°C and 30% RH)					0.012	0.038

Taken from Acoustics and Psychoacoustics by David Howard and James Angus, Focal Press 2001

Material	125Hz	250Hz	500Hz	1kHz	2kHz	4kHz
50mm Acoustic Foam	0.08	0.25	0.60	0.90	0.95	0.90
100mm Acoustic Foam	0.20	0.70	0.99	0.99	0.99	0.99
50mm Mineral Wool (Medium Density)	0.20	0.45	0.70	0.80	0.80	0.80
Plaster on brick	0.013	0.015	0.02	0.03	0.04	0.05
Cotton Drapes draped to half area. 15oz/sq yd	0.07	0.37	0.49	0.65	0.54
Foam backed carpet on concrete	0.05	0.16	0.44	0.70	0.60	0.40
Heavy carpet plus heavy foam underlay on concrete	0.15	0.25	0.50	0.60	0.70	0.80
Coarse concrete	0.36	0.44	0.31	0.29	0.39	0.25
Painted concrete	0.01	0.05	0.06	0.07	0.09	0.08
Wood floor	0.15	0.11	0.10	0.07	0.06	0.07
Window glass	0.35	0.25	0.18	0.12	0.07	0.04
Plate glass	0.18	0.06	0.04	0.03	0.02	0.02
6mm glass	0.10	0.06	0.04	0.03	0.02	0.02
Plaster on brick	0.013	0.015	0.02	0.03	0.04	0.05
9mm plasterboard over 20mm air gap	0.30	0.20	0.15	0.05	0.05	0.05
Brickwork	0.05	0.04	0.02	0.04	0.05	0.05
Vinyl flooring	0.03	0.04	0.05	0.04	0.05	0.05
Breeze block	0.25	0.40	0.60	0.50	0.75	0.50
LF panel absorber	0.28	0.22	0.17	0.09	0.10	0.11
Perforated Helmholtz absorber using 4″ depth with mineral wool damping, 0.79% perforation	0.40	0.84	0.00	0.16	0.14	0.12
Perforated Helmholtz absorber using 8″ depth with mineral wool damping, 0.79% perforation	0.98	0.80	0.52	0.21	0.16	0.14
Broadband absorber consisting of 1″ fibreglass slab at mouth of 7″ deep cavity	0.67	0.98	0.98	0.93	0.90	0.96
Padded seat (unoccupied)	0.10	0.20	0.25	0.30	0.00	0.30

Taken from Creative Recording Volume 2 by Paul White, Sanctuary Publishing 1999

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