3D sound field visualization and modal characterization of a reverberant chamber

This paper investigates the three-dimensional sound field inside a reverberant chamber with the aim of characterizing its modal behavior and assessing its impact on standardized sound absorption measurements. Scanning measurements were conducted over a horizontal plane for two different source positions to evaluate source-position dependency. The combined visualization of sound pressure, and three-dimensional sound intensity provides insight into local modal structures and acoustic energy flow within the chamber. Based on the spatial distribution of sound pressure, regions corresponding to local pressure maxima were identified and used to define a subset of microphone positions for reverberation time measurements. These results were compared with measurements obtained using randomly distributed microphone positions, following the procedures of ISO 354 for the determination of sound absorption. The experimental findings enhance the understanding of reverberant room acoustics and demonstrate that the estimated absorption coefficients remain relatively unbiased when microphone positions are selected at local pressure maxima, indicating that the sound absorption estimation is robust against the local modal behavior of the reverberant testing chamber.