The adaptive beam-tracing algorithm

Abstract

The most popular models to predict sound propagation in architectural spaces involve the tracing of rays, images, or beams. Most current beam-tracing methods use conical or triangular beams that may produce overlaps and holes in the predicted sound field. Hence a new method has been developed whereby the shape of reflected beams is governed by the shape of reflecting surfaces so as to produce a geometrically perfect description of the sound propagation for halls with occluding surfaces. The method also facilitates the calculation of diffuse sound propagation by managing the energy transfer from a specular model to a diffuse model. This adaptive beam-tracing method compares well with other methods in terms of speed and accuracy.

Beam Tracing with Refraction

“…Diffuse reflection and diffraction of sound are not currently incorporated in the BTR. These phenomena are already solved with the beam tracing method, and published by several authors (Farina, 2000;Drumm, 2000;Funkhouser et al, 1998;Tsingos, Funkhouser, 2001). The BTR has been specialized to include the refraction.…”

“…He also introduced a method of radiant exchange for calculating diffuse reflections. The next step in the development of the beam tracing method was taken by Farina (1994;2000) and by Drumm (2000). They introduced an adaptive beam division algorithm that divided a beam into several smaller beams when it encountered more than one reflective plane.…”

“…The ending triangle of the beam is the place where the beam leaves the entity, if it is refracted, or the place where the beam is returned back to the entity, if it is reflected. In classical beam tracing, such as the method developed by Drumm (2000) and Funkhouser et al (1998), beams have polygonal cross sections. The advantage of such an approach is that fewer beams are needed to trace a scene than are necessary with triangular beams.…”

A forward-advancing wave expansion method for numerical solution of large-scale sound propagation problems

“…Similar to the ray tracing technique are the the beam tracing methods [12,13,20] obstructed by several surfaces [19]. As for ray tracing, diffraction contri bution modelling is a problem for beam tracing methods [20].…”

“…Ray tracing is a well known algorithm in acoustic modelling, specially in the area of room acoustics [12][13][14][15][16]. Ray trace techniques are based on geometri cal acoustics, where the sound is supposed to act like rays.…”