École Nationale Supérieure de
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Résumé

Currently available software for room acoustics simulating use mostly asymptotic methods as ray-tracing which has approximations that turn its results unreliable in low-frequencies. One of these software, ICARE, is used by Saint-Gobain to simulate the acoustical influence of their materials in a room and to present an auralization of such room for the potential clients. The objective of this work was to develop a tool that can improve the accuracy of their simulations for low-frequencies. We developed the fem4room, an open-source finite elements solver oriented for room acoustics simulation. For that, the finite elements formulation were applied for the wave-equations with the needed impedance surface boundary conditions, a monopole source was implemented and Newmark's method for solving it in time was used. The tool was validated with theoretical results as room modes, impedance tube, and Sabine's theory of reverberation. The calculation time is comparable to available solutions for the finite elements method (FEM). For solving the linear system resulted from the FEM, we used an iterative method (GCROT), feeding it at each time-step with the previous solution. We did measurements of the impulse response in a reverberant room with absorbing materials at the walls and calculated its reverberation time (RT60). We used this RT60 as ground-truth to test our solution and compare its accuracy with ICARE by one-third octave frequency bands. The bands were from 50Hz to 800Hz. The CAD model of the room and the absorbing coefficients were fed to the both simulation solutions. The solution fem4room seems promising for being applied in simulations workflows. Further analysis of the results in low frequency, verification of the spectral content, and how to combine the results from the different methods would be the next steps for this work.

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• Combining Ray Tracing and Finite Elements for Room Acoustics Simulation (deposited 13 nov. 2020 12:09) [Actuellement Affiché]