Index of content:
Volume 120, Issue 4, October 2006
- ARCHITECTURAL ACOUSTICS 
120(2006); http://dx.doi.org/10.1121/1.2338814View Description Hide Description
A numerical model is proposed to predict the reverberant sound field in a system of two coupled volumes that are connected through an open aperture. The model is based on the numerical implementation of a diffusionmodel that has already been applied to predict the sound-energy distribution and the sound decay in single rooms. In comparison with the statistical theory, the proposed approach permits the prediction of the sound field by taking into account the sound source location and the receiver locations as well as the transition from one room to the other at the coupling aperture. Moreover, the diffusionmodel results match satisfactorily the experimental data in terms of sound-pressure level and reverberation times, both in the room containing the source and in the receiving room. Simulations with a ray-based model are also carried out, leading to results similar to those of the diffusionmodel, but at a cost of larger computation times.
120(2006); http://dx.doi.org/10.1121/1.2214134View Description Hide Description
The purpose of this paper is to examine the potential of poroelastic materials to control the low frequency noise radiated outside a parallellepipedic cavity enclosing a point source. The enclosure consists of five rigid walls and one flexible plate, all of which may be treated with a porous slab. The Biot-Allard theory, three equivalent fluid approaches and a locally reacting assumption are used to model the porous medium. The response of the system is calculated using a finite element model for all the components. The two issues addressed are the modeling of a porous material in a complex structure and the control of the sound radiated outside the cavity. Concerning the first point, calculations confirmed the validity range of the locally reacting assumption and prove the relevance of a limp porous model for unbonded plate treatments. Regarding the second issue, the sound power reduction obtained with the treatment of nonvibrating walls is compared to that achieved when treating the plate. The efficiency of the different mounting conditions of the porous slab to the plate is also discussed. Finally, the calculation of the dissipated powers inside the system provides a crucial information to optimize the sound absorbing treatment.