Frequency Dependent Absorbing Boundary Implementations in 3D FDTD Room Acoustics Simulations
The University of York
Monday 1 june, 2015, 11:40 - 12:00
0.3 Copenhagen (49)
Finite Difference Time Domain (FDTD) based simulation of acoustic wave propagation within a bounded space is commonly used in room acoustics modelling research. Although accurate at low frequencies, full audio bandwidth solutions remain computationally demanding despite significant efficiency gains based on GPU implementations. Acoustic boundary modelling has also received some considerable attention in the literature, with frequency dependent absorbing and diffusing boundary implementations based on a digital impedance filter (DIF) FDTD grid termination demonstrating results closely approximating real-world materials. The DIF does, however, add complexity, both in terms of the filter design process, normally based only on octave band absorption coefficient data, and due to the required implementation, where potentially high-order DIFs are used. DIFs therefore add additional processing and memory loads to an already demanding algorithm, and require particular consideration in optimised parallelisation schemes. This paper develops an alternative solution, recently proposed in the literature, where an efficient, octave-band, frequency independent boundary implementation is used. Results are computed simultaneously in parallel for each band and summed via a filter bank to arrive at a total response. This method is compared with the DIF approach based on the final impulse responses produced and the computational requirements of both algorithms.
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