Low-Noise and Ecological Motor Vehicles for Cities

The paper evaluates criteria for measurement of vehicle noise in urban areas. In general, noise pressure levels are not adequate for universally valid measurements because they depend upon characteristics of the surroundings; for such measurements, different evaluating means are required. For urban measurements, the location of the subjects of vehicle noise, such as passengers, pedestrians, and local residents, are considered. The acoustic characteristics of the immediate surroundings are critical to vehicle noise and this fact also demands new noise-testing procedures. The influence of engine and vehicle parameters on noise-levels is discussed, especially that of statistic periodicity of engine operations. Low frequency noise is especially difficult to control by conventional methods and will require different sound-dampening approaches. Throughout the paper special attention is given to previous sound-testing procedures and studies, and the effectiveness of specific approaches is compared.