Noise Source Localization Investigation in High Speed Train Based on Microphone Array

摘要

The method to use planar array to identify the noise sources in high speed train is described. Through investigating the noise sources in high speed train, it is shown that the important noise sources are situated at windshield, door, air outlet, joints between headwall and sidewall. The spectra characteristics and sound pressure contour of these noise sources are obtained. The sound energies of these noise sources are concentrated in the frequency range of 0～1000 Hz mainly. Some effective countermeasures against interior noise of high speed train are suggested. Interior train noise decreases the comfort for the passengers inside the vehicle. As speeds increase, noise inevitably also increases. It has been known that rolling noise levels increase at a rate of 30log10v (with v the speed). The noise from aerodynamic sources increases more rapidly with speed, increasing at typically around 60log10v, and above 300 km/h aerodynamic noise becomes significant [1-2]. In order to carry out effective countermeasures against high speed noise, a detailed knowledge of the distribution and the properties of the sound sources is necessary. One of the methods to identify the different train sources is to carry out noise measurements with devices such as antennae. An acoustic antenna is a series of microphones, whose outputs are processed in order to focus on acoustic sources and to enable an acoustic map to be drawn. Accurate measurements on high-speed train usually require the development of specific tools [4-6]. The main sources identified from different studies on various high-speed trains are the pantograph, the recess of the pantograph, the inter-coach spacing, the bogie, the nose of the power car, the surfaces, the rear power car, louvres, ventilators[7-11]. However, it has not been reported how to locate interior train noise sources, which is critical for interior noise abatement and reduction design. In this paper, a planar microphone array is introduced and used to study the noise sources and spectra characteristics in high speed train.