Practical estimation of sound reflection of a panel with a reflection coefficient.

Abstract

In an auditorium, an absorbent boundary is used in order to control the reverberant field. Its reflection composes a part of the early reflections and can not be neglected to estimate the transfer function. The sound reflection coefficient is defined as an unknown function of the integral equation of the first kind, referring to the reflection of a surface element on a rigid plane. It is very difficult with the equation to determine the coefficient which changes depending on incident and reflection angles. When a panel covered with a surface having a reflection coefficient which changes continuously and smoothly is large enough, the kernel function leaves the contribution around the specular reflection point and then the coefficient there can be separated experimentally. The reflection of a panel of limited dimension with such a reflection coefficient is approximately obtained by the convolution of the coefficient and the reflection of the rigid panel at the same position of the panel. Calculated and measured results are compared in the time and frequency domains. This method is also applied to a convex and a concave panel covered with a layer of such a reflection coefficient. The reflection of a panel with a mutual arrangement of strips of two different reflection coefficients is also discussed.