Part 1 of GB/T 16404-1996 Determination of sound power level of noise sources by sound intensity method in focused acoustics. It specifies discrete point Measurement mode, which is suitable for a variety of noise sources. Measurement principles based on sound intensity principle are elaborated, and specific requirements for measurement at discrete points are clarified, including measurement point selection principle, quantity determination method, and measuring instrument accuracy and calibrate are also stipulated. Standardize sound intensity data collection and subsequent sound Power level calculation process, provide basic specifications for accurate measurement of noise source sound Power level, and help acoustics research, industrial noise reduction and other work.