Research on Influencing Factors of Sound Absorption Coefficient in Reverberation Chamber

In the automotive industry, testing the sound absorption coefficient of acoustic materials through reverberation chambers has been widely used. The advantage of this method is that sound waves are incident on the surface of acoustic materials randomly, which is more in line with actual engineering. At present, most of the reverberation chamber design and construction refers to the international standard ISO 354-2003. However, although the design indicators of the reverberation chamber have already met the requirements of the standard ISO 354-2003, there are still some differences between the test results of different reverberation chambers on the same group of samples to be tested, and sometimes the differences are so big they affect the engineering applications. In this paper, the sound absorption coefficients of the same group of samples in different reverberation chambers are tested, and there are some differences in the sound absorption coefficients. Also, the sound absorption coefficients of a variety of samples of different materials in several different reverberation chambers were tested, confirming that there is a phenomenon of poor repeatability of the sound absorption coefficient of the reverberation chamber test. To optimize the poor repeatability of the sound absorption coefficient of the reverberation chamber test, the diffuser in a reverberation chamber is arranged in many different ways. In each reverberation chamber with a different layout, the sound absorption coefficient of the same piece is tested. The diffuser layout of the reverberation chamber was adjusted to the optimal arrangement according to the test results of the sound absorption coefficient. Next, each factor in the testing process of the sound absorption coefficient that may have an impact on the test results is examined separately, and the influencing factors are analyzed. Finally, the optimal test scheme for testing the sound absorption coefficient in the reverberation chamber is given. More importantly, an acceptable margin of error is given regarding the sound absorption coefficient of the reverberation chamber test material.