Improved algorithms and methods for room sound-field prediction by acoustical radiosity in arbitrary polyhedral rooms

Abstract

This paper explores acoustical (or time-dependent) radiosity--a geometrical-acoustics sound-field prediction method that assumes diffuse surface reflection. The literature of acoustical radiosity is briefly reviewed and the advantages and disadvantages of the method are discussed. A discrete form of the integral equation that results from meshing the enclosure boundaries into patches is presented and used in a discrete-time algorithm. Furthermore, an averaging technique is used to reduce computational requirements. To generalize to nonrectangular rooms, a spherical-triangle method is proposed as a means of evaluating the integrals over solid angles that appear in the discrete form of the integral equation. The evaluation of form factors, which also appear in the numerical solution, is discussed for rectangular and nonrectangular rooms. This algorithm and associated methods are validated by comparison of the steady-state predictions for a spherical enclosure to analytical solutions.

Optimum absorption and aperture parameters for realistic coupled volume spaces determined from computational analysis and subjective testing results

“…Alternative geometries commonly seen in single volume halls, such as fan-shape and vineyard styles, could also be studied. Different modeling methods, such as physical scale modeling, radiative transfer models, 32,33 diffusion models, 34,35 and finite difference time-domain methods, 36 could be used to make additional conclusions about the influence of architectural parameters on DSE and its subjective impression. Aspects of the subjective response to DSE could be further investigated as well.…”

Overview of geometrical room acoustic modeling techniques

“…59 The basic principle of presenting such reflection characteristics is the same as that of the above-mentioned BRDF model, but it is called the reflection matrix. The diffuse reflection variant of the equation was further refined by Nosal et al 60 to contain a source term that enables the computation of timeenergy responses, whereas the previous versions were only used to study the energy balance in the room.…”

“…158 A major step in acoustic radiosity was taken in 2004 when Nosal et al presented, in detail, how the technique can be used to predict the sound field in non-rectangular rooms with ideally diffusely reflecting boundaries. 60 The paper also includes validation against analytical solutions in a spherical enclosure. The algorithm computes the radiation density, which is also known as the radiance in later papers, and follows the same iterative propagation principle, as illustrated in Fig.…”

3D acoustic simulation inside closed rooms bounded by non-parallel floor and ceiling surfaces

“…The ray tracing method [1,2], the image source method [3,4], beam tracing [5] and acoustic radiosity [6,7] are some of these methods. One review of them can be found in [8].…”