Research On Mechanism And Method Of Ultrasonic Directivity Measurement Of Acoustic Array

Urban traffic noise is becoming more and more important in urban sound environment and people's physical and mental health with the increase of traffic intensity,traffic vehicle holding and road network.This type of vehicle noise is a combination of acoustic radiation from multiple sound sources.It is characterized by multiple sources,strong directivity and discontinuity.The noise is serious and the measurement is more difficult than stationary source.How to effectively measure the sound field has become a problem of acoustic measurement,but also a key basis for urban planning.Based on this,this paper proposes that the acoustic array super-directivity measurement is to optimize the acoustic array super-directivity based on the acoustic field directivity characteristics so as to improve the acoustic source resolution and sound field measurement capability of the acoustic array.The main work of this paper includes:(1)Based on the analysis of existing literatures,the background,social and scientific significance and value of acoustic array super-directivity measurement are pointed out.At the same time,the research status of super-directivity measurement of acoustic array is introduced in detail.(2)The basic concepts of the super-directivity of the acoustic array are given in detail,the formation process of the super-directivity of the acoustic array and its key parameters and characteristics are clarified,and the corresponding constraint conditions are deduced.Finally,the signal-to-noise ratio is used as the weight to construct the super-directivity mathematical model of the maximum signal-to-noise ratio acoustic array,and the key parameters of the model are discussed.(3)The directivity measurement of the moving sound field is studied,and the directivity characteristics of the point source and the R(t)of the key parameters are analyzed under uniform and linear acceleration.At the same time,the construction and evaluation parameters of the super-directivity acoustic array of the moving sound field are given through research and analysis.(4)The directivity function expressions of rectangular array and circular array are deduced and analyzed respectively by directivity simulation.The directivity characteristic of the array is compared with that of the irregular shape array,and have arrived at a better directivity array.A randomly generated array of circular microphones is presented,and the performance of this random array is better than that of the above array.(5)Finally,to further verify the validity of the method and the robustness of the super-directivity,experimental measurements were made.According to different experimental requirements,laboratory and field experiments were carried out respectively.The experimental results show that the super-directivity acoustic array has the characteristics of maximum signal-to-noise ratio,narrow main beam lobe width and good side-lobe suppression,and can accurately locate sound sources with different sound intensities.The weak sound source provides theoretical and technical guidance.