A study on acoustical design criteria of the balcony configuration in auditoria

观众席上经常设置阳台悬挑。阳台下空间的截面形状是影响观众席音质的重要因素之一。然而，悬挑下的声学特性还没有得到澄清，到目前为止，还没有一个被普遍接受的阳台配置的声学标准。第二步，通过心理声学实验考察阳台上反射延迟时间(DELTAt)和反射水平(L)的主观效应，因为阳台的存在对阳台早期反射结构的影响被认为是导致观众席阳台下声学缺陷的原因之一。模拟的音乐声音有一个或两个反射作为刺激。结果表明，随着DELTAt和L的减小，声像的听觉尺寸变小。接下来，使用具有从水平方向和从上方两个方向的早期反射的模拟音乐声音作为刺激。结果表明，在横向能量分数不变的情况下，随着反射能量垂直分量的增加，包络变得Stroger。这些事实表明，主乐团上方天花板上缺乏早期反射是干扰阳台下良好音质的一个因素。

A balcony overhang is frequently set up in auditoria. The sectional shape of the under-balcony space is one of the most important factors for good acoustics in auditoria. The acoustical properties under the overhang, however, have not been clarified yet and there is so far no generally accepted criteria for acoustical of the balcony configuration. The object of this study is to make clear the relation between the shape of the balcony and the acoustical properties.As the second step, the subjective effects of the delay time(DELTAt) and the level(L) of reflections from upside is examined by psycho-acoustical experiments, because the structure of early reflections from upside, which is affected by the presence of a balcony, is regarded as one of the causes of acoustical defect under the balcony in auditorium. Simulated music sounds with a single or two reflections are uesd as stimuli. The results show that auditory size of sound image becomes smaller as DELTAt and L are smaller. Next, simulated music sound with early reflections both from horizontal directions and from upside are used as stimuli. The results show that envelopment becomes stroger as vertical component of reflected energy increases when lateral energy fraction is constant. These facts suggest that lack of early reflections from ceiling above main orchestra is a factor for disturbing good acoustics under the balcony.