Analyzing Noise Pressure Level at Different Setting Location of Microphone on Tire/Surface Noise Measurement

This study is performed to investigate change of sound pressure levels under the different setting place of microphone at the tires using different vehicle types when tire/surface noise is measured. Tire/surface noise is measured using passenger car, SUV, bus, and truck at both asphalt and concrete pavements where are prohibited the traffic flow.The surface microphone is used to measure tire/surface noise installed near to tire and then the tire/surface noise is measured at various vehicle speeds between 60 km/h and 100 km/h. For small vehicles, tire/surface noise is measured from 8 microphones that is installed right and left sides at front and rear tires. For large vehicles (bus and truck) tire/surface noise is measured from 6 microphones that is installed right side, center and left sides at front tire. Based on the tire/surface noise measurement at different locations of microphone using different types of vehicle, sound pressure level is changed from 3dB/A to 9dB/A. However, in this study, tire/surface noise is influenced by the types of vehicle and the place of microphone. Therefore, it is should be review the place of microphones under different types of vehicle in order to measure accurate tire/surface noise using NCPX method.