本文提出“虚墙”法作为众所周知的虚声源法的对偶，并将它应用于车行隧道和城市街道混响声场的交通噪声计算。根据这个概念，由单车种等间距分布的车流所产牛的声场可等效于位于一对假想的刚硬墙壁之问的单一车辆所产牛的声场。这对虚墙与隧道或街道的边界形成一个围闭空同，使得经典室内声压级计算公式可以应用于计算交通噪声混响声压级。本文还给出两个应用实例与实测数据相比较。

Loudness is one of the most essential parameters for assessing the acoustical quality of an auditorium. But owing to the lack of an authentic criterion, it remains unresolved how to evaluate the loudness in concert halts. In this paper LpF, the mean forte sound pressure level of tutti-sound is suggested as a criterion to describe the loudness in a hall. The prediction procedure of the LpF value distribution in a hall is demonstrated, Comparison between predicted and measured LpF levels is given. Tentative optimum and allowable LpF values for concert halls are also doscissed.