双传声器声强测试技术是一种对环境条件要求较低的声学测试技术 ,广泛应用于现场条件下的声功率测量、声源识别、故障诊断等方面 ,但是很强的背景声也会对声强测试产生不良的影响 ,产生较大的误差。本文分析了在内燃机车动力室的条件下 ,测量柴油机表面辐射噪声声功率时测点的声强测量误差的来源 ,得出了动力室内背景声很强是测量误差的主要来源的结论 ,从理论上证明了相位失配是造成背景声影响声强测量精度的主要原因 ,并给出了可行的测量方法 Dual microphone sound intensity test technology is a kind of acoustic test technology that requires less environmental conditions, which is widely used in acoustic power measurement, sound source identification, fault diagnosis and other aspects in the field conditions, but strong background sound will also affect the sound Strong test produces adverse effects, resulting in greater error. This paper analyzes the sources of measurement error of sound intensity at the measuring point when measuring the sound power of radiated noise on the diesel engine under the condition of the power chamber of a diesel locomotive and concludes that the strong background noise in the power chamber is the main source of measurement error. It is proved that the phase mismatch is the main reason for the accuracy of the sound intensity caused by the background sound and gives a feasible measurement method