High potential of small-room acoustic modeling with 3D time-domain finite element method

Abstract

Applicability of wave-based acoustics simulation methods in the time domain has increased markedly for performing room-acoustics simulation. They can incorporate sound absorber effects appropriately with a local-reaction frequency-dependent impedance boundary condition and an extended-reaction model. However, their accuracy, efficiency and practicality against a standard frequency-domain solver in 3D room acoustics simulation are still not known well. This paper describes a performance examination of a recently developed time-domain FEM (TD-FEM) for small-room acoustics simulation. This report first describes the significantly higher efficiency of TD-FEM against a frequency-domain FEM (FD-FEM) via acoustics simulation in a small cubic room and a small meeting room, including two porous-type sound absorbers and a resonant-type sound absorber. Those sound absorbers are modeled with local-reaction frequency-dependent impedance boundary conditions and an extended-reaction model. Then, the practicality of time-domain FEM is demonstrated further by simulating the room impulse response of the meeting room under various sound absorber configurations, including the frequency component up to 6 kHz. Results demonstrated the high potential and computational benefit of time-domain FEM as a 3D small room acoustics prediction tool.

A Review of Finite Element Methods for Room Acoustics

“…Okuzono et al [90] implemented a frequency-dependent absorbing boundary using the ADE method and found good agreement between FEM solutions in the time domain and the frequency domain. Okuzono and Yoshida [137] modeled the frequency dependence of both LR and ER materials in the time domain.…”

“…The coupled model was used to simulate the measurement of impedance in an impedance tube, and good agreement with analytical data was found. Okuzono & Yoshida [137] considered the FEM in the time domain for small room acoustics. They modeled frequency-dependent LR and ER sound absorbers, and simulated impulse responses up to 6 kHz.…”

Time-domain extended-reaction microperforated panel sound absorber modeling for acoustics simulation by finite element method

“…Wave-based room acoustics simulation using the finite element method (FEM) attracts intense interest because of its high flexibility for boundary shape modeling. Recently, by virtue of the development of highly efficient solvers with a sound-absorbing boundary considering the frequency-dependent complex-valued surface impedance of soundabsorbing materials, it is becoming possible to apply timedomain finite element method (TD-FEM)-based numerical solvers to the broadband acoustic modeling of realistic rooms [1][2][3][4][5][6][7]. However, for more precise simulations of room acoustics, it is crucially important to use extendedreaction (ER) sound-absorbing models able to incorporate both the frequency and incident-angle dependences of absorbing materials.…”

“…Additionally, thin materials such as permeable membranes and microperforated panels (MPPs) have been modeled with interior impedance boundary conditions [15][16][17]. Nevertheless, recent work [6] has demonstrated that TD-FEM has benefits for computational times for large-scale problems such as real-sized 3D room acoustics simulation. Therefore, developing a TD-ER model for TD-FEM to realize high-efficiency wave-based room acoustics simulation is an attractive topic.…”

“…The proposed ER model is based on interior impedance boundary conditions with frequency-dependent transfer admittance, a time-domain counterpart of the frequencydomain model proposed in an earlier report [16], and an extension of the TD-ER model of permeable membranes [22]. We also describe the specific implementation procedure of the present time-domain ER model of MPP absorbers into an implicit TD-FEM formulation [3][4][5][6] for room-acoustics simulation. The point of novelty of the present work is that this report is the first to propose a general formulation of the implicit TD-FEM dealing with a time-domain ER model of MPP absorbers.…”