Abstract
For development of acoustic model technique as a design tool of auditorium, evaluation method of the echo oscillogrammes on the subjective echo disturbance was investigated. The 1000 decay curves having single echoes, which have a time delay of 50 ms to 170 ms, with various sequence of diffusing reflections were made in a special model box (fig.6). The test sound used was 2 ms pulse of warbling tone of 10 kHz. From the results of hearing test, dependence of echo disturbance on the intensity of the diffissing sound as well as the delay times and the level differences of the echoes referred to the primary sound were looked for. Two parameters, R/D and h/w in fig.12, were adopted to establish a quantitative relation of the evaluation of echoes to the shape of echo diagrams. By using these two parameters, the critical lines at the threshold of absolute perceptibility of an echo as a function of the delay time were obtained in fig.13 and fig.14. These acoustic model techniques wave applied in 1 : 10 scale models of six multipurpose auditorium and the influences of the room shape on the echo oscillogrammes were examined. So we could find the effect of modification in the design of various parts of the room to improve decay curves varied with the fundamental shapes of auditorium.
