SOUND ABSORPTION COEFFICIENT MEASUREMENT METHODS IN REVERBERATION ROOM AND IMPEDANCE TUBE

Sound absorption materials are very often used for space design in order to reduce the noise level and adjust the acoustic characteristics of the space depending on its purpose. Therefore, knowledge of the acoustic quantities that characterize sound absorption materials is of crucial importance. The most commonly used acoustic quantity is the sound absorption coefficient, which can be determined using standardized methods and methods used only for research purposes. This paper will provide an overview of the most commonly used standardized methods for determining the sound absorption coefficient: the reverberation room method and the impedance tube method. Since the impedance tube method, which provides the normal incidence sound absorption coefficient, is more suitable when developing new absorption materials, and in practical applications, it is desirable to know the random incidence sound absorption coefficient, this paper discusses approaches for predicting the random incidence sound absorption coefficient based on the acoustic parameters of the sound absorption materials measured in an impedance tube.