Modeling of Complex Geometries and Boundary Conditions in Finite Difference/Finite Volume Time Domain Room Acoustics Simulation

Abstract

Due to recent increases in computing power, room acoustics simulation in 3D using time stepping schemes is becoming a viable alternative to standard methods based on ray tracing and the image source method. Finite Difference Time Domain (FDTD) methods, operating over regular grids, are perhaps the best known among such methods, which simulate the acoustic field in its entirety over the problem domain. In a realistic room acoustics setting, working over a regular grid is attractive from a computational standpoint, but is complicated by geometrical considerations, particularly when the geometry does not conform neatly to the grid, and those of boundary conditions which emulate the properties of real wall materials. Both such features may be dealt with through an appeal to methods operating over unstructured grids, such as finite volume methods, which reduce to FDTD when employed over regular grids. Through numerical energy analysis, such methods lead to direct stability conditions for complex problems, including convenient geometrical conditions at irregular boundaries. Simulation results are presented. Index Terms-Finite difference time domain method, finite volume methods, room acoustics.

Passive time-domain numerical designs for room acoustics simulation

“…Under a regular arrangement of cells over the problem interior, FVTD schemes reduce to certain well-known families of FDTD schemes, while allowing for fitting of unstructured cells at the room boundary, and incur little to no additional computational expense over FDTD methods. See [2,3] for more on the basics of FVTD methods.…”

“…Wave-based time domain methods, such as finite difference (FDTD) [1] and finite volume (FVTD) [2,3] methods allow, in theory, for complete solutions to the problem of room acoustics simulation. Despite their high computational cost, modern computer hardware allows for audio rate simulation, for large acoustic spaces, in a reasonable amount of time.…”

Binaural Reproduction of Finite Difference Simulations Using Spherical Array Processing

“…The simulation was repeated for axial (Ω 0 ≡ (π/2, 0)) and side-diagonal (Ω 0 ≡ (π/2, π/4)) source incidence angles. For comparison with an ideal PWD beamformer, results were also generated in closed form using (11). To exclude any artefacts caused by spatial sampling, all arrays are studied below their aliasing limit.…”

“…Nonetheless, modeling the fine geometric structure of the pinna [8], [9], [10] requires a considerably higher grid resolution than for modeling interaural cues. This imposes a significant computational burden and may also introduce errors when nonconformal boundary conditions are employed [11]. In addition, when embedding a listener in the grid, the transfer functions of the room and the head are jointly computed.…”

Influence of voxelization on finite difference time domain simulations of head-related transfer functions

“…Some limitations of the staircase-like boundaries a) Electronic mail: sebastian.prepelita@aalto.fi were shown 20 only for simple geometries and cases. The current work studies the influence of the voxelization process in the context of FDTD HRTF simulations for cases where the geometry is acquired through a laser scanning process.…”