TABLE 23.1 Absorption coefficients for various materials Frequency (Hz) Material 125 250 500 1000 2000 4000 Concrete block, unpainted 0.36 0.44 0.31 0.29 0.39 0.25 Concrete block, painted 0.10 0.05 0.06 0.07 0.09 0.08 Glass, window 0.35 0.25 0.18 0.12 0.07 0.04 Plaster on lath 0.14 0.10 0.06 0.05 0.04 0.03 Plywood paneling 0.28 0.22 0.17 0.09 0.10 0.11 Drapery, lightweight 0.03 0.04 0.11 0.17 0.24 0.35 Drapery, heavyweight 0.14 0.35 0.55 0.72 0.70 0.65 Terrazzo floor 0.01 0.01 0.02 0.02 0.02 0.02 Wood floor 0.15 0.11 0.10 0.07 0.06 0.07 Carpet, on concrete 0.02 0.06 0.14 0.37 0.60 0.65 Carpet, on pad 0.08 0.24 0.57 0.69 0.71 0.73 Acoustical tile, suspended 0.76 0.93 0.83 0.99 0.99 0.94 Acoustical tile, on concrete 0.14 0.20 0.76 0.79 0.58 0.37 Gypsum board, 7 in. 0.29 0.10 0.05 0.04 0.07 0.09