Determination of vehicle noise source levels

Abstract

In 1974 the Florida Department of Transportation participated in a study sponsored by the Federal Highway Administration to determine vehicle source levels. This paper reports the findings of a second study designed to extend the range of the operating speeds of the vehicles in question down to 20 mph (32 kph). A total of 11 sites were included in the study with vehicles operating between 20 to 61 mph. The subsequent data were analyzed to provide distributions of maximum passby sound levels and reference energy mean emission levels as a function of speed for automobiles, medium trucks, and heavy trucks. The data were analyzed over the entire speed range and on the basis of 5 mph speed band to provide empirical relations for use in predictive models. Of particular interest was the extent to which the choice of these formats influenced the noise source relationships and, of more significance, the extent to which the introduction of low-speed data which were not previously available influenced source level relationships. [Work supported by the Florida Department of Transportation.]