GB/T 9661-1988 is a standard for aircraft noise measurement around airports. The standard specifies the scope of application of measurement, that is, the area around the airport. Specifies the accuracy and performance requirements of the instruments required for measurement, such as acoustic measurement instruments. Specifies the measurement environmental conditions to ensure that background noise and other factors do not interfere with the measurement results. Describes the principle of measurement point layout, covering different directions and distances of airport runways. It also describes the impact of aircraft flight status on measurement and the corresponding Measurement mode, providing a scientific and unified method for accurately assessing aircraft noise around the airport, and assisting airport planning and noise prevention.