This paper investigates low frequency sound of a two-span continuous steel box girder bridge, three-span continuous steel plate girder bridge and three-span continuous prestressed concrete bridge. Those three bridges were selected as candidates to be constructed crossing a rural town since they satisfy conventional design criteria. In this study, velocity responses of bridges were estimated by a three-dimensional traffic-induced vibration analysis, and those velocity responses were used in sound propagation analysis by means of boundary element method (BEM), and the time-domain low frequency sound was examined by means of the inverse fast Fourier transformation (IFFT). Investigations demonstrated that the two-span continuous steel box girder bridge showed the lowest sound pressure level among three bridges.