Research On Three-dimensional Directional Active Noise Control Based On Phased Array

The control area of traditional active noise control is relatively fixed,and when the control direction and the axis of secondary sound source are too large,the effect will decline sharply,so it is difficult to achieve directional noise reduction at a large angle in three-dimensional space.Based on the speaker array technology and phased array theory,this paper studies the realization of three-dimensional directional sound source from the theoretical basis,simulation optimization and experimental test,applies the sound source as a secondary sound source to active noise control,compares the sound field before and after control by using finite element simulation software,and carres out experimental verification in semi free field,The directional active noise control in three-dimensional space is realized.According to the acoustic stealth requirements of underwater targets,an active echo suppression method is proposed.The sound field before and after control is simulated and calculated,the sound field characteristics before and after control are compared,the active echo suppression is realized in the pipeline,and the reflected wave suppression in the pipeline is realized,which has important theoretical significance and engineering application value.Starting with the theory of phased array,this paper introduces the superposition and coherence of sound waves,deduces the directivity and deflection of loudspeaker array based on the superposition principle,discusses the influencing factors of directivity based on simulation,and carries out the directivity experiments of linear loudspeaker array and plane loudspeaker array in free field and semi free field,Compared with the simulation results,the reliability of the system is verified.In order to verify the advantages of directional sound source,the spatial sound field before and after the control of non directional sound source and directional sound source is simulated by finite element software.Based on FXLMS algorithm,the speaker phased array is used as the secondary sound source for active noise control,and the threedimensional active noise control based on phased array is realized in the semi free field.Considering the echo suppression of underwater target,the target surface sound field is the superposition of reflected wave and direct wave,and the difficulty of control is the extraction of control signal.A double sensor delay signal extraction method is proposed in the pipeline,and the sound field characteristics before and after control are numerically simulated to verify the feasibility of this method,and the active echo suppression is realized in the pipeline.Based on the numerical simulation and experimental results,it can be seen that the phased array of speakers can realize the bunching of sound waves,change the nondirectional sound source into a strong directional sound source,and change the directivity of the array sound source by changing the phase difference of the array elements.Taking it as the secondary sound source of active noise control can obtain better control effect in a wider range.Less impact in non-controlled areas;Separate the incident wave and reflected wave of the superimposed sound field in the pipeline,realize the active echo suppression in the pipeline,obtain the echo control effect of more than 15dB in the range of 300-900hz single frequency signal,and eliminate most of the influence of reflected wave in the pipeline.Combined with three-dimensional directional sound source,it can realize the active suppression of target echo under special applications for incident waves in different directions,It has strong application value in military,widens the application field of active noise control,has important theoretical significance and engineering application value,and has great innovation.