Frequency Dependent Absorbing Boundary Implementations in 3D FDTD Room Acoustics Simulations
Invited paper
The University of York
Monday 1 june, 2015, 11:40 - 12:00
0.3 Copenhagen (49)
Abstract:
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.