Using diffusion equation model to analyze advanced sound energy decay in reverberation chamber

Abstract

In the room acoustics measurement process, a non-diffused sound field is neglected in conventional chamber-based studies of absorbing materials, which reduces accuracy and can even produce inconsistent results. An additional discrepancy about the definition of a complete diffuse sound field around the border of the target absorption material under test is revealed by an analysis of the energy flow in the reverberation room[Schroeder \& Manfred R., JASA, Vol 31, pp. 1407-1414 (1959)]. Currently, one can easily create a model simulating the sound energy flow inside the reverberation chamber with the help of a diffusion equation model, especially for measurements of random incidence absorption coefficients. This model also offers a lighter computational load at roughly the same level of precision as wave-based methods. In order to acquire the energy flow of the chamber more effectively than wave-based simulation models, a technique for applying the diffusion equation model to the modeling of reverberation chambers is presented in this study. For highly absorbent materials, further investigation reveals that one-twelfth of mean free route length is the meshing condition that is deemed realistically correct for getting random incidence absorption coefficient. With Jing's boundary condition and the simulated energy flow, an inverted computation of a high absorption coefficient is made achievable. Due to the accuracy and greater order of energy decay simulation, it is now possible to determine absorption coefficients without the interference of an incomplete diffuse sound field by comparing the results of simulations with measurement data.