Based On The Acoustic Characteristics Analysis Of The Rectangular Cavity Of The Acoustic Black Hole Structure

Noise exists in all aspects of our life.Once the noise exceeds 70 decibels,it will cause great interference to people’s learning and life.Being under the noise source for a long time will even harm people’s health and lead to the occurrence of diseases,so the control of noise becomes necessary.In this paper,from the perspective of passive noise control,referring to the structure of acoustic enclosure and sound insulation board,and considering the actual installation requirements,the acoustic characteristics of rectangular cavity with openings are studied.The research work is as follows:In this paper,by introducing trigonometric function as an auxiliary term,the expression of sound pressure under three-dimensional improved Fourier series is constructed.At the same time,the Lagrange function and Rayleigh-Ritz energy principle of the open cavity system are combined to solve the natural frequency and unknown coefficient of the expression of sound pressure,and finally the expression function of sound pressure inside and outside the cavity is obtained.The results of theoretical expression of rectangular cavity with a circular hole are compared by using Virtual Lab software and experimental method,and the correctness of the model of rectangular cavity with a circular hole is proved.At the same time,the simulation method is used to study the sound pressure response value of rectangular cavity with circular hole under different parameters.It is found that the existence of the hole can accelerate the decline of the sound pressure value in the cavity.In this paper,the acoustic black hole structure is introduced,and the theoretical model of open acoustic black hole rectangular plate is established.The vibration reduction and noise reduction effect of acoustic black hole on rectangular plate is analyzed from the vibration point of view.At the same time,the energy accumulation effect of acoustic black hole is simply explained according to the geometric acoustics.COMSOL Multiphysics is used to simulate the rectangular plate of an acoustic black hole and the correctness of the simulation results is verified by experiments.By changing different boundary conditions and model parameters to analyze the vibration characteristics of the rectangular plate of the acoustic black hole,it is found that the natural frequency increases with the increase of boundary constraints,while the natural frequency decreases with the increase of density,and the number of holes increases.It is found that the more the number of holes,the smaller the displacement vibration amplitude,the better the effect of vibration reduction and noise reduction of the acoustic black hole.According to the effect of vibration reduction and noise reduction of acoustic black hole,the acoustic black hole is applied to the rectangular open hole cavity,and a three-dimensional model of the rectangular open acoustic black hole cavity is established.The acoustic characteristics of the rectangular open acoustic black hole cavity are analyzed with Virtual.Lab acoustic software.The feasibility of the simulation method is verified by comparing with the experimental results.At the same time,it is found in the simulation analysis that the sound pressure response of the rectangular cavity with an acoustic black hole has a symmetrical relationship,and the smaller the size of the rectangular cavity with an acoustic black hole,the greater the resonance frequency of the cavity.Through the comparison of different open-ended rectangular cavity,it is found that the open-ended acoustic black hole has more advantages in noise reduction of the whole open-ended cavity system.