Testing according to ASTM C423 and ISO 354 still raises specific questions about the mounting conditions and other specifications of the measurement procedure in the reverberation chamber. Room dimensions, source and receiver positions, and other factors lead to deviation of results between laboratories. In addition, counter-intuitive test results can occur as a result of sample shape and arrangement, often leading to very high absorption coefficients, and difficulties relating random incidence coefficients to their normal incidence counterparts. This is the well-known battle over coefficients that has been debated for more than 100 years. When it comes to testing of baffles, even more uncertainties are added, and one of the most important is the practical question of how to use test results in calculations with prediction models. We present several computational approaches to determine absorption data of several baffle configurations and discuss the results related to absorption and scattering for different angles of sound incidence and for the random average compared to ASTM C423 test results.
Jaramillo et al. (Wed,) studied this question.