Effects of room shape and diffusing treatment on the measurement of sound absorption coefficient in a reverberation room

In this paper, the measurement of sound absorption coefficient of acoustical materials in a reverberation room is investigated by numerical analysis based on the ray-tracing method. As a result, it has been confirmed that the sound absorption coefficient of the same specimen can much differ by the differences of room shape and by the effect of the sound diffusers. In order to evaluate the degree of sound diffusivity in a reverberation room, the angular dependence of the sound power incident to the room boundary and to the surface of the specimen have been calculated. From the result of the numerical analysis, the relationship between the measurement of sound absorption coefficient of materials and the diffusivity of the sound field in a reverberation room has been examined.