Coefficients of Absorption for Common Materials
(from Penn Foster) ⭐⭐⭐⭐⭐
Material Coefficient of Absorption
Perforated acoustic ceiling material 60%
Heavy curtains (D) 50%
Carpeting (B) 20%
Wood (A) 5%
Plaster 3%
Clay tile 3%
Concrete (C) 2%
The answer is D. Heavy curtains ✅