Non-cuboid Iterative room optimizer

Abstract

In past years, various iterative optimization programs emerged to separately determine the optimal room ratios, sources and listening positions of perfectly reflective cuboid rooms, using 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. This presentation describes the current status of a program called NIRO, that offers a solution to those issues, by using the Boundary Element Method (BEM) to compute the frequency response from 20–200 Hz, 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 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.