A Study of Acoustical Design of Under-Balcony Space in Auditoria

本研究的目的是明确悬挑下阳台形状与声学性能之间的关系，并最终推导出阳台配置的声学设计标准。假设建阳台引起的声场物理变化主要是上层早期反射能量的减少，测量阳台下早期反射的方向特性。结果表明，垂向反射能量占早反射总能量的比例很小。然后利用实测数据进行心理声学实验。结果表明：听觉包络随着反射能量垂直分量的增大而增强，而横向能量分量不变；下一个。采用基于几何声学的计算机模拟方法，计算了不同阳台开口深度和高度时礼堂模型的冲击响应。悬垂对基本声学指标（SPL、C_<80>、TS和LE）的影响不明显。这意味着需要另一个指标来评估阳台下经常感知到的听觉包络的缺乏。研究了早期反射波的方向特征。得到构型指标d/h与垂直分量占早反射总能量ERv之比的关系，其中d和h由声源位置、接收点位置和阳台边缘位置几何定义。将ERv的差分系数应用于这一关系，发现悬架下的听觉包络度与主乐团相当的d/h的最大极限在0.7 ~ 1.0之间。可以认为这是礼堂阳台的设计标准。

The purpose of this study is to make clear the relation between the shape of balcony and acoustical properties under the overhang, and ultimately to derive an acoustic design criteria for balcony configuration is auditoria. On the assumption that a physical change of the sound field caused by building a balcony would be primarily a reduction of the energy of early reflections from upside, the directional characteristics of early reflections under the balcony is measured. The results show that the ratio of vertical component to total early reflection energy is very small under the overhang. Then psycho-acoustical experiments by using the measured data are perfoemed. The results show that auditory envelopment becomes stronger as the vertical component of reflected energy increases while lateral energy fraction is constant. Next. impulse responses are calculated in models of auditorium by means of computer simulation based on geometrical acoustics when the depth and the height of balcony-opening are varied. The evident effect of overhang can not be found in basic acoustical indices (SPL,C_<80>, TS and LE). This means that another index is necessary for evaluating the lack of auditory envelopment which is often perceived under the balcony. The directional characteristics of early reflections are examined. As a result, the relation between the configuration index of d/h and the ratio of vertical component to total early reflection energy ERv is obtained, where d and h are geometrically defined by the positions of sound source, receiving point and balcony edge. Applying the difference Iimen of ERv to this relation, it is found thet the maximum limit of d/h, in which the degree of auditory envelopment under the overhang is equivalent to that in main orchestra, is between 0.7 and 1.0. It can be thought that this is a design criteria of balcony in auditoria.