Title: On measurements to locate sources of aerodynamic and wheel/rail noise generated by high-speed trains
Abstract: This investigation was carried out to locate noise sources at high-speed trains (up to 250 km/h) with two different microphone systems. For higher frequencies a concave-mirror directional microphone, using seven microphones in the focus plane, was operated. For lower frequencies the acoustic telescope—a microphone array—consisting of 14 microphones was used, which has been developed at University of Cambridge, and which allows to follow the train electronically with the focus of the system. Radiated noise was measured laterally and above the train. It was thereby possible to isolate wheel/rail noise from aerodynamic noise. At higher frequencies even very small single noise sources, as, e.g., aerodynamic noise from the bumpers could be identified. The potential for reducing wheel/rail noise down to the level where aerodynamic noise sources dominate is shown. It is demonstrated that directional microphone systems are valuable tools to distinguish between different simultaneously radiating noise sources. Directional microphones therefore are also an essential aid attenuating noise at its source. [Work supported by the German Bundesministerium für Forschung and Technologie, and the Deutsche Bundesbahn.]