The Maximum Radiation Noise Source Location Method And Experimental Research For A Moving Vehicle

The precondition of moving noise control is to identify the moving source accurately. At present, the main methods for identify the noise source have the elimination method (dismount parts method and lead coverture method), sound intensity measurement method, spectral decomposition method, nearfield acoustic holography method etc. The elimination method's trial test operation is complex, test period is long and the accuracy is low; The sound intensity measurement method's has a great effect for a single sound source or compound sound sources that have small interact, but it can't identify the complex compound sound sources such as the car's. The spectral decomposition method is usually measure with elimination method, it more be apply to the destine frequency range, trial test is complex, test period is long, the data processing operating quantity is great, the method cannot identify the sound sources whet they have the same frequency; The nearfield acoustic holography method identify the noise sound source by measure the holography data of measured face that abut on sound source face, and reconstruct the three-dimension sound pressure field by nearfield acoustic holography. Above mentioned methods has their localization: they can identify the stable state and static sound noise source, but cannot identify the car accelerate passing noise. Main achievement that this paper obtains: 1.A method is developed and tested for the determination of the location of the maximum radiation noise source (MRNS) in moving vehicles. In the method, the sound signals of a moving vehicle, on which a reference sound source is attached, are measured with a cross-array of receivers on one side of the road. Analyzing the instantaneous correlation function of the sound signals yields the instantaneous time delay between the reference source and the MRNS, from which the location of the MRNS is determined. The stimulation and experiments results prove the validity of the method. Using this method, the vehicle maximum noise source frequency of this experiment is 86 Hz, in being away from vehicle head 1. 0±0.3m, is the vehicle motive power assembly. 2. Have analyzed the two vehicle's interior noise data by using velocity domain, power spectrum and periodogram methods, reached the conclusion by comparing their noise level and noise trait that under equal condition, the noise level in A vehicle is higher than the noise level in B vehicle obviously and both enhance with the velocity. Increasing; the A's static and dynamic background noise more heavy than B's, A proximate linear relation between the A and B sound pressure level and their velocity; the A's wind, air inlet, driver surrounds center also have a proximate linear relation with velocity; One of A vehicle noise exceptional reason is in low speed background noise exceptional; The dynamic background noise of two vehicles increases with the increase of speed; The background noise power density of two vehicles has similarity , spreads mainly in the frequency of 200-1800 Hz ; It is gently that wind noise power density distribution is compared , have no outstanding formant, its power density follow speed increase. The partial increase of high frequency; discussing the possible relation between the A's inner and the outer pinpoint (air inlet, driver surrounds center, wind) noise level.