Geluid-emissie door personenauto's en vrachtwagens op autosnelwegen.

Reference sound levels, corresponding with source strength, have been measured of passenger cars as a function of speed and of different kind of trucks as a function of speed and gross weight. From measurements and calculations of the time history of the sound level of passing vehicles, it appears that passenger cars can fairly will be described as acoustical monopoles. For trucks more or less systematical differences are found between the calculated and measured time history.