The airport project is one of the development projects on the environmental impact assessment (EIA) requested list by law in Thailand. The airport noise impact assessment procedures are selectively proposed by a consultant whom conducts the EIA reports for the airport development project, freely. Airport noise assessment procedures have been following the Noise Exposure Forecast (NEF) for more than 50 years, proposed by the American Consultant. There is none of any rules and regulations specifying the noise descriptor and its calculation for airport noise in Thailand. NEF is now a current noise descriptor to contribute in the calculation of airport noise levels and their contours, making a proposed contour map for determining the airport noise mitigation measures and monitoring plan on the EIA report of the proposed airport development project and its expansion. Day-Night Noise Levels (Ldn) and Day Evening-Night Noise Levels (Lden) using Sound Exposure Levels (SEL) measurement were also proposed to the land use compatibility consideration in the future. Their measurements and calculations have been on the research sales to propose specific rules on the calculation and measurement of airport noise assessment in Thailand.