The noise directivity of railbuses

In this paper the noise generated by the railbuses is analysed. To find the directivity index of the railbuses a method of its estimation was proposed. This method is based on the assumption of symmetrical changes in the sound level during the passage of a railbus. The four directivity indices were analysed: monopole, cosine, squared cosine and cubed cosine. We find that the monopole directivity is the best to describe the noise generation by the moving railbuses.