Arrival direction of late sound and listener envelopment in concert auditoria

本研究的目的是探讨晚声到达方向与感知听者包络（LEV）之间的关系。在消声室内用三维模拟声场进行了一系列心理实验。首先，分别研究了来自四个基本方向的迟能量对可感知LEV的影响。结果表明，横向声级与LEV的相关性最高，而从听者头顶和身后传来的后期声音与LEV的相关性也非常强。其次，通过实验明确了后期声的定向能量分量对LEV的贡献程度。结果表明，除了侧向声外，后面和头顶的后期声也会显著影响LEV。此外，定向晚能量比随总晚能量水平的变化而变化。结果表明，横向、后向和架空晚能比对LEV的贡献程度。在礼堂中进行了客观测量，以阐明与听者包络相关的晚期声音的方向性特征。定向传声器的测量值揭示了实际声场中横向、纵向和垂直晚能量的水平变化范围。竖向分量的水平衰减系数最大。此外，为了解释到达接收器的晚声的空间平衡，还考虑了定向晚能量比。为了实现被声音图像包围的感觉，还应该考虑适当的后期反射方向分布。需要进一步研究后期声定向分布的最佳条件。

The purpose of this study is to investigate the relation between the arrival direction of late sound and perceived listener envelopment (LEV). A series of psychological experiments were conducted with three-dimensional simulated sound fields in an anechoic chamber. Firstly, the effect of late energy arriving from four fundamental directions on perceived LEV was individually investigated. The results show that the lateral sound level gives the highest correlation with LEV, while late sound arriving from overhead and behind the listener also correlates to LEV very strongly and positively. Secondly, the experiments were conducted to make clear the degree of contribution of directional energy components of late sound to LEV. The results show that not only lateral level but also the late sounds from behind and overhead affect LEV significantly. Furthermore, directional late energy ratios were varied with a constant level of total late energy. From the result, the degree of contribution of lateral, back and overhead late energy ratios to LEV was found. Objective measurements were performed in auditoria to clarify the directional characteristics of late sounds, which correlated with listener envelopment. The measured values with directional microphones reveal the ranges of the level variation of lateral, longitudinal and vertical late energy in real sound fields. It is also found that the level attenuation coefficient of vertical component is highest. Furthermore, directional late energy ratios are considered in order to account for the spatial balance of late sound arriving at a receiver. A proper directional distribution of late reflections should also be considered in order to realize the feeling of being surrounded by sound images. Further research on the optimum conditions for the directional distribution of late sound is needed.