22 - Acoustic Modeling, Ray Tracing, and Auralization

Abstract

Chapter 22 discusses computer modeling of rooms using ray tracing and auralization. The discussion begins with early testing using scale models, spark testing, and finally ray tracing. The latter begins with the casting of rays and reviews methods of determining the number of rays and how to deal with reflection from surfaces. As the number of rays grows, these models transition into a lumped parameter approach to simplify the calculations. Next we examine the details of ray tracing using mathematical models of rays, surfaces, and their intersections, first dealing with planes and then moving on to polygons and other geometric shapes. Once the ray has intersected a surface, the reflection is examined with and without absorption. Finally diffusion is introduced along with the concept of a scattering coefficient. From there multiple reflections and edge effects can be examined. Auralization is one of the final products where a dry musical signal is convolved with the impulse response of the room.