HRAE标准68-78中描述了一种使用单个采样管测量风机辐射到管道中的声功率的方法。据报道，管道内风机的声功率结果与将同一台风机引入混响室时获得的声功率结果之间存在一些分歧。超过截止频率时，管道内风机声功率结果已被报告低于混响室结果，并且据说这种差异随着频率的增加而增加。为了确认这些趋势并找到可能的校正系数，将采样管法与新的双麦克风强度技术进行了比较，以确定配备消声终端的管道中的绝对风扇声功率。建议修订ASHRAE标准68-78，包括适当的校正系数。引用:ASHRAE交易，第88卷，第2部分，加拿大多伦多

A method using a single sampling tube for measuring the acoustic power radiated by a fan into a duct is described inASHRAE Standard 68-78. Some disagreement has been reported between such in-duct fan sound power results and those obtained for the sound power when the same fan is ducted into a reverberation room. Above cutoff frequency, the in-duct fan sound power results have been reported to be below the reverberation room results and this difference has been said to increase with frequency. To confirm these trends and to find possible correction factors, the sampling tube approach was compared with a new two-microphone intensity technique to determine the absolute fan sound power in a duct fitted with an anechoic termination. Recommendations are made for revision ofASHRAE Standard 68-78to include suitable correction factors.