ATTENUATION OF OUTDOOR NOISE DUE TO AIR ABSORPTION AND GROUND EFFECT

industrial noise (stationary sources) is assessed by the sound level, L-A, and road traffic noise and railroad noise (moving sources) are de scribed in terms of the time-average sound level, L-AT, which depends upon the sound exposure level, L-AE. To predict their values in an ope n space with minimum computer time, simple models of air absorption an d ground effect have been developed: the air absorption with the fully determined equivalent absorption coefficient, alpha, the ground effec t with the A-weighted power level, L-WA, and the ground coefficient, g amma. The estimates of both parameters, L-WA and gamma, are based on L -A and L-AE measurements. The theory yields L-A and L-AT as functions of the distance to the receiver and its height above the ground surfac e. (C) 1997 Elsevier Science Ltd.