Determination of railway noise contribution based on noise source identification and acoustic transfer function

Abstract

Environmental noise standards of noise for Japan's bullet trains, known as Shinkansen, are among the most stringent in the world. To reduce train noise and meet these standards, the contribution ratio of each noise source to the total noise at the observation point provisioned by the Japanese government, 25 m from the nearest track must be determined. Although previous studies have determined the contribution ratio using multiple omnidirectional microphones and a 1-dimensional microphone array positioned at the observation point, we propose a new method to evaluate the contribution ratio by combining the noise source identification with an acoustic experiment. The microphone array clearly measures the noise source distribution around a vehicle using signal processing of the deconvolution algorithm, indicating that bogies and pantographs are the dominant aerodynamic noise sources. The transfer function of the radiated sound between the sources and observation point was determined in the acoustic model experiment with a viaduct and noise barrier. The contribution ratio obtained should be useful in assessing the noise reduction from shape modification.