Moving point source—A simple model for predicting statistical sound levels in the neighborhood

Abstract

When predicting the noise produced by moving sound sources (e.g., vehicles, airplanes, etc.) sound-level statistics can be helpful to describe the situation. However, the common sound models only yield the average sound level, and under special circumstances, also the maximum sound level. The calculation model moving sound source also gives sound level and the level-versus-time diagram. For the calculation, first the paths of the sound sources have to be digitalized and divided into parts. Each part will be represented as a point sound source which is active during a certain time slot, which again is based upon the velocities of the moving objects. Sound propagation from all point sources to the point of emission is calculated by using ISO or equivalent standards. This leads to the time versus level diagram and (when the steps from one to another point source are small enough) to the desired statistical levels. The described model, named the moving sound source, has no limitations. It could be easily integrated in commercial sound propagation calculation programs. It was successfully used for the approval of a new racetrack in Germany. Also, the new DIN 45684 (noise of small aircraft) is based on it.