THE THEORY OF SOUND INTENSITY OR ACOUSTIC NOISE FROM FREELY FLOWING TRAFFIC HAS BEEN INVESTIGATED BY SEVERAL AUTHORS. IT IS POSSIBLE TO CALCULATE THE CUMULANTS OF SOUND INTENSITY EXACTLY FOR THE COMMONLY USED MODEL AS WELL AS THE CHARACTERISTIC FUNCTION, BUT AN EXACT INVERSION TO OBTAIN THE PROBABILITY DENSITY FUNCTION DOES NOT APPEAR POSSIBLE. SEVERAL APPROXIMATIONS TO THE FULL DISTRIBUTION OF SOUND INTENSITY HAVE BEEN PROPOSED. THE PEARSON CURVE METHODOLOGY WAS APPLIED TO DETERMINE THE FULL PDF AND FOUND THAT THE BEST FIT IS GIVEN BY A BETA DISTRIBUTION. THIS IS TRUE WITH AND WITHOUT EXCESS ATTENUATION DUE TO ATMOSPHERIC OR GROUND ABSORPTION AND WHEN A MIXTURE OF VEHICLE TYPES IS PRESENT. THE EXACT AND APPROXIMATE DISTRIBUTIONS WERE COMPARED INDIRECTLY BY COMPARING HIGHER MOMENTS NOT USED TO FIX PARAMETERS.
Abstract