A systematic analysis was carried out on the acoustic behaviour of railroad coaches. Radiation of air-borne sound as well as structure-borne sound transmission from the wheel/rail contact area to the car body was investigated in laboratory and stationary tests and during test runs at high speeds (160-250 km/h). The aim of the experiments was to find out how much the individual components of the trailing bogie contribute to the transmission of structure-borne sound and the radiation of air-borne sound. A rank ordering of the individual transmission paths from the axle bearing to the bogie frame was set up. An identification of the main noise sources and an indication of the frequency range in which they are important was possible.