Abstract
The "echo-stripe diagram" was proposed in order to investigate the "echo-time diagram" with respect to the requencies of sound in rooms. If we plot as abscissa the lapse of time between the instant of observation of the direct sound and that of one of the peaks or dips in an individual reverberation curve, and ordinate the frequency of sound, then connect vertically the points thus plotted, an "echo-stripe diagram" such as shown in Figs. 1 and 2 is obtained. A study was made of the diagram thus obtained from the pulsed glide displays observed at the Daiichi Seimei Hall in Tokyo. It was clarified that the continuous vertical stripes conspicious in the diagram was the combined effect of the focussing action on sound of the concave hard wall of "Horizont" on the stage and the multiple reflection of sound between the "Horizont" and the plane plywood panel placed behind the audience. A method was also devised of obtaining the "echo-stripe diagram" directly on photographic film with the same apparatus as used for obtaining the pulsed glide display. The display obtained by this method was named the "longitudinal pulsed glide display" to distinguish it from the pulsed glide display presented by Mr. Somerville. The two devices should both have their useful purposes in the investigation of the acoustics of rooms.
