オーディトリウム空間の幾何的対称性と音場特性に関する研究 : 拡散形状モデルによる幾何音響解析

概要

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The purpose of this study is to investigate the relation between acoustic characteristics of sound field and the fundamental room shape of auditoria from the point of view of symmetrical property of the space, and to make clear the acoustical validity of asymmetric room shape in acoustic design. In this paper, the objective parameters, namely early-to-late energy ratio C80, lateral energy fraction LF and the spatial distributions of reflection levels are investigated in 17 hall models, whose ceilings and side walls are entirely diffusive, by means of geometrical acoustic simulation. The results show that there is a significant difference in the attenuation of reflected energy due to the source-receiver distance between symmetric and asymmetric models, and particularly, the increase in late-arriving sound level GL is found at the rear seats in the asymmetric halls. These are caused by an increase of the number of geometrical reflections arriving at the time interval approximately from 100 to 200 ms after the direct sound. The present results definitively confirmed our previous findings in the hall models with flat boundaries. Finally, more options and possibilities in acoustic design methods can be realized by considering the contribution of asymmetric configuration to the uniformity of sound fields.
九州共立大学の論文