1983 年 4 巻 1 号 p. 27-33
If the first reflection from a rigid curved surface hits other panels, or the inside of a concave panel has other specular reflection points, discrete reflections among these multiple reflections change their transfer functions very much. It is already shown that multiple reflections of a geometrical wave and boundary waves are separately calculated between rigid plane panels. An impulse response from a rigid curved panel resembles that of a rigid plane panel. A discrete reflection around the specular reflection point of the first panel is replaced by an equivalent image point source and the second reflection between rigid curved panels is estimated by the first reflection of it. The multiple reflections inside a rigid concave panel with large curvature and the contribution of wide area around the specular reflection point can be also approximately calculated by the equivalent image point source from the strength of the first reflection. These calculated results are compared with measured ones in the time and frequency domains.