Elucidation of Noise Near the Bogie Using Sound Source Visualization Method

Abstract

There are many sources of railway vehicle noise generated by equipment such as gear devices installed in the narrow space of a bogie frame under the floor of a vehicle. Therefore, it is difficult to separate the sound sources onboard a vehicle with a sound level meter, and up to now there no method has been developed for separating the sound sources. As a method to solve this problem, we are working on applying a sound source visualization method to the noise measurement of railway driving devices. The 4-channel beamforming method (BF method) and the envelope intensity method (EI method) are used as sound visualization methods, and the test results are compared. This paper reports on the results of noise measurement on a driving device using a sound source visualization method in bench-scale testing, and the results of a study to improve accuracy. We confirmed that the beamforming method has excellent imaging stability for transient sounds, and that image processing using multiple small microphone arrays improves the imaging accuracy of the BF method.