Simulation of traffic noise both indoors and outdoors based on an integrated geometric acoustics method

Abstract

An integrated geometric acoustics method is presented for calculating both indoor and outdoor traffic noise distributions. This approach is divided into three phases: spatial subdivision, path generation, and noise calculation. First, spatial subdivision is applied outdoors. Then, sound paths are generated outdoors via beam tracing and indoors via ray tracing through structure trees. For indoor receivers, sub-beams that enter the building are defined, and their paths are generated by searching the hunting zone. Finally, using the determined paths, both indoor and outdoor noise values can be calculated. A case is used to evaluate the accuracy at various frequencies; the method yields more accurate results with mid-high-frequency sounds compared with low-frequency sounds both indoors and outdoors; at the dominant frequency of 630 Hz of traffic noise, the indoor and outdoor average errors are 1.45 dB and 0.55 dB, respectively. Moreover, the effects of the building position and the interior structure on traffic noise are discussed. The following conclusions are obtained: 1) The noise levels in the front portions of buildings are much higher than those in the rear portions, in both the entire space and individual rooms, and as the floor number increases, the attenuation increases as the distance and complexity of the path increase. 2) The influence of the interior structures on the noise distribution is strong. With the same area for each type of room, the noise effects in the bedrooms and the drawing room in strip-type houses are the strongest; after comprehensive consideration, the foursquare-type house is recommended.