INFLUENCE OF GROUND EFFECT AND REFRACTION ON ROAD TRAFFIC NOISE

Ground effect and refraction modify geometrical spreading. In the pres ent study a simplified model of ground effect is applied. Refraction i s analyzed for the motionless atmosphere with a linear sound speed pro file. Noise generated by constant speed road traffic is assessed by th e time-average sound level, L-AeqT. The model of L-AeqT prediction con tains free parameters that are estimated from noise measurements at th e sire in question. The model makes possible the prediction of L-AeqT at an altitude of a few tens of meters above the ground surface, withi n the range of a few hundred meters from the road. Contours of L-AeqT = constant in the vertical plane represent the radiation pattern of ro ad traffic noise. (C) 1997 Elsevier Science Ltd.