人们越来越关注建筑物中的低频噪声。然而，相关声源的声功率通常不包括125 Hz倍频带以下的任何数据，因为现行的ANSI标准系列（$1.30-$1.35）及其ISO对应标准在确定声功率的同时，没有设置任何低频限值，也没有提供任何关于125 Hz倍频带以下频率测量不确定性的信息。在混响室测量中，至少存在两种类型的低频问题:（1）难以获得有效的空间平均声压；（2）声源看到的声阻抗对其声功率输出的影响。关于第二种类型的已发表文献包含相互矛盾的信息。 这个问题不仅对标准化设备声音测量和评级程序很重要，而且对安静空调系统设计中正确应用设备声功率评级也很重要。引文:研讨会，ASHRAE交易，第95卷，pt。1989年，芝加哥

There is a growing concern with low-frequency noise in buildings. Sound poweratings for the sources involved, however, typically do not include any data below the 125 Hz octave band because the present series of ANSI standards ($1.30-$1.35) and their ISO counterparts for the determination of sound power, while not setting any low-frequency limits, do not provide any information on measurement uncertainties for frequencies below the 125 Hz octave band. In reverberation room measurements, there are at least two types of Iow-frequency problems: (1) difficulties in obtaining a valid space average the sound pressure and (2) effects of the acoustic impedance seen by the source on its sound power output. The published literature on the second type contains conflicting information. This issue is important not only for standardizing equipment sound measurement and rating procedures, but also for the proper application of equipment sound power ratings in the design of quiet airconditioning systems.