Absorption coefficient of building materials in different conditions

Abstract

Absorption coefficient of building elements are measured by ISO 354 – Measurement of sound absorption in a reverberation room. In cope with the standard, test specimen not smaller than 10㎡ is installed on the hard floor of a reverberant chamber which has the volume around 200㎥. However building materials sometimes are installed as partition walls at openings between rooms and sometimes consist of a part of exterior walls instead of used as simple coverings. Furthermore there are cases that one module is larger than 10㎡ or very thick to be accommodated in the normal reverberation chamber of 200㎥. Absorption coefficients are measured according to such different conditions. Specimens are installed and measured on standard hard floor in a medium volume of reverberation chamber, same condition but in a far larger volume of chamber, at the opening between a reverberant chamber and another reverberant chamber, and at the opening between a reverberant chamber and coupled free field anechoic chamber. Result shows that the absorption coefficients of building materials are quite different when measured in different conditions.