An experimental and theoretical study of the modelling of road traffic noise and its transmission in the urban environment

This paper describes experiments conducted on the modelling of traffic noise using a $\text{1}\text{80th}$ scale model of a subdivision of a city. The emphasis in this study was on the correct evaluation of ground absorption effects. There were essentially four phases to the study. First, the applicability of various scaling law regimes was examined. It was shown that $\text{1}\text{80th}$ scaling using air as a transmission medium was at least a practical choice. The second phase concerned itself with the choice of materials for the model, particularly that which was to simulate the ground. An impedance measuring apparatus was developed and used to test materials. The third part of the work concerned itself with the development of an anechoic enclosure and a sound source to simulate traffic noise; modulated Hartmann whistles were used for this purpose. Finally, a model of part of a residential area of Calgary was built and sound transmission measurements obtained. These results were compared with field measurements. It was shown that good agreement existed between the field and model measurements.