Experimental validation of a diffusion equation-based modeling of the sound field in coupled rooms

Sound modeling in coupled rooms (i.e., two acoustically coupled rooms separated by an open area) has attracted considerable attention in the past. However accurate and operational models are still needed, principally when three or more rooms are coupled. In recent papers, a diffusion equation-based model has been applied to unusual room shapes. For the coupled rooms geometry, this diffusion model has been validated successfully by comparison with the classical statistical theory in a parametrical study of the coupling parameters [Billon et al., J. Acoust. Soc. Am. 116, 2553 (2004)]. In the present work, the diffusion model results are validated by means of a comparison with experimental results, both in terms of sound attenuation and reverberation time. A comparison is also provided with results given by the statistical theory and a ray tracing program. For this purpose, experiments have been conducted in two coupled classrooms with two different sound source locations. The results show a very good agreement between the diffusion model and the experiments. Conversely, the statistical model is not valid for modeling accurately the sound field distribution and decay in both coupled rooms. At last, the diffusion model runs much faster than the ray tracing program.