Petrolli, R, D'Antonio, P, Storyk, J, Hargreaves, JA 
ORCID: https://orcid.org/0000-0003-4736-7507 and Betcke, T
2020,
Non-cuboid iterative room optimizer
, in: Forum Acusticum, 7th - 11th Dec 2020, Online.
Abstract
In small room acoustics, the range from the first resonant frequency up to the Schroeder frequency is dominated by modal resonances and the Speaker-Boundary Interference Response (SBIR). Both are very sensitive to the positioning of sources, receivers and room geometry. The source locations determine which modes are excited, and the listener locations determine which modes are heard. In past years, various iterative optimization programs emerged to separately determine the optimal room ratios, sources and listening positions of perfectly reflective cuboid rooms, through the use of the image-source model. Despite its fast computation times, this approach does not account for scattering, phase change at the boundary and cannot be extended to non-cuboid rooms.
The present work presents a solution to those issues by using the Boundary Element Method (BEM) to compute the frequency response at low-frequencies, considering the effects of the boundary’s complex admittance and all acoustical elements inside the room. With BEM as its
engine, a Room Optimization Genetic Algorithm (ROGA) was developed to optimize source and receiver positions simultaneously with the room geometry, aiming to present the best possible acoustic environment given imposed restraints. To control the room’s temporal decay, low-frequency acoustic treatments were added to the BEM model. By
using Transfer Matrix Models, the acoustical behavior of different multilayered treatments can be modeled and inserted into the BEM simulation to evaluate the change in the room’s acoustic field and in the frequency response at the receiving positions. 3D waterfall plots illustrate the temporal decay following optimization. Examples will be
presented.
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