Absorption coefficients of common materials at several frequencies

frequency (hertz)

material 125 250 500 1,000 2,000 4,000

concrete 0.01 0.01 0.02 0.02 0.02 0.03

plasterboard 0.20 0.15 0.10 0.08 0.04 0.02

acoustic board 0.25 0.45 0.80 0.90 0.90 0.90

curtains 0.05 0.12 0.25 0.35 0.40 0.45