According to the different testing environment, measuring instrument and measuring purpose, there are several standards for the surface sound pressure method to measure sound power, and the measurement accuracy of different standards is different. Reverberation chamber precision method, anechoic chamber and semi-anechoic chamber precision method can obtain 1 (precision); The comparison of the special reverberation test chamber method, the nearly free field above the reflecting surface engineering and the hard wall test chamber method can obtain 2 (engineering). 2 or 3 (engineering or simple) can be obtained by the simple method of envelope measurement surface above the reflecting surface; The field comparison method is only 3 (simple) accurate. Surface sound pressure method to measure sound power requires the use of multi-channel signal analyzer, the number of channels according to the measurement requirements selected, as the number of measuring points, high accuracy.