Application Of The Array Technology In Identification Of The Noise Sources Of The Train

In order to reduce the noise of urban rail transit, we must firstly understand the causes for the noise generated, such as the location of the sound source, type, frequency characteristics, etc., after understanding and controlling over the noise characteristics and radiation laws, we can adopt the appropriate measures to control the noise of the train. Therefore, theoretical studding, simulating, testing and verifying the subject of identification of the sound source of running train is of great significance.Combined with project of research on identification of sound sources of urban rail train, based on the experience of previous studies, the simulation and testing and verifying of train noise are discussed, the theoretical approaches and technological research of identification of noise source of the elevated train are carried out.This paper mainly includes 3 parts:Firstly, the theory system is set up in beamforming method to rebuild the sound field. According to beamforming method and the basic principles of radiation of moving sound sources, the elementary theory of array signal analysis of sound field of the running rail train is described, the de-Dopplerization procedure is also studied through non-equality time delay and resample, then, the time-domain and frequency domain methods of beamforming in identifying moving sound sources are studied in detail. Through removing autocorrelation of microphone signal, modified time domain beamforming method is brought about. Secondly, the simulative calculation system of beamforming method is set up and the validity of the method is verified. Based on engineering conditions, the star-shaped acoustic array is designed and its characteristics are researched. After that, the simulative calculation is done and the results of Recognition algorithms in different conditions are compared. Theory was validated in detail by the simulation system, which can be used in practice efficiently.Eventually, identification of sound sources of low-speed ground train and elevated train is solved by beamforming method in the paper. Using existing equipments of the laboratory and star-shaped array, noise tests are implemented. Main noise sources maps of low-speed ground train and elevated train can be obtained.