Determination of acoustic ray paths in enclosed spaces

Abstract

Equations were derived to calculate the reflection points of acoustic rays emanating from a source to a receiver. Reflection points for up to three reflections could be determined if the location of the source, receiver and all reflecting surfaces were known. Assuming a point source, the distances along the calculated ray paths were used along with the power level of the source and the absorptive characteristics of all the reflecting surfaces to determine the sound pressure levels at specified receiver locations. A computer program was developed to perform the necessary calculations for reflection points and sound pressure levels. The output was in the form of ray tracing plots which showed the unique reflection paths for up to three reflections and the sound pressure levels at each receiver location. Comparisons were made between predicted and calculated sound pressure levels in a rectangular parallelopiped shaped room and a long narrow hallway.

The results of this investigation showed a promising potential in the area of sound pressure level predictions and the use of ray tracing plots to provide a means of reducing the sound pressure levels. A particularly interesting point of the program was its ability to handle very irregularly shaped rooms which include slanted surfaces.