Optimization Method And Design Of Sound Absorption Structure For Shunted Loudspeaker

The efficient absorption of low-frequency broadband noise is a key issue in noise control.Passive sound-absorbing materials and structures are difficult to absorb noise efficiently in a limited scale,and active sound-absorbing technologies have the problems of insufficient stability and high cost when applied.The semi-active acoustic structure based on shunt loudspeaker technology has the advantages of high stability and excellent sound absorption performance,and has a wide range of application prospects.In this thesis,an in-depth study of the shunt loudspeaker acoustic structure is carried out,and an acoustic absorption optimization algorithm based on exhaustive and backtracking search is proposed,and a thin and light loudspeaker is designed and fabricated with the goal of acoustic absorption,and the correctness of the acoustic absorption optimization algorithm and the design idea of the thin and light loudspeaker is verified through experiments.The main work of the paper is as follows.The sound absorption equation of the shunt loudspeaker and the stability condition of the system are derived,and the stability of the circuit is simulated using circuit simulation software.Since the sound absorption structure of the shunt loudspeaker contains several system variables and some of the variables are nonlinear,it is difficult to optimize the sound absorption using the analytical method,and an optimization algorithm based on exhaustive and backtracking search is proposed.The results show that the parameters of commercially available commercial loudspeakers for acoustic applications are not suitable for use as efficient acoustic devices.A method is proposed to obtain the intrinsic parameters of a shunt loudspeaker by impedance tube test,and the accuracy of the method is verified by the agreement between experimental results and theoretical predictions.Taking a shunt loudspeaker acoustic structure as an example,an exhaustive and backtracking search algorithm is used to obtain an optimal set of stiffness,resistance,inductance and capacitance parameters.The measured value of the average absorption coefficient of the optimized shunt loudspeaker in the 100-450 Hz range is greater than 0.65,which is a significant improvement compared with the absorption performance of the shunt loudspeaker in the disconnected or short-circuited state,verifying the correctness of the proposed algorithm.The rigid back cavity with a diameter of 100 mm and a depth of 50 mm is used as the volume constraint,and 100-450 Hz is used as the target frequency band to optimize the sound absorption calculation of the shunt speaker acoustic structure.According to the calculation results of the production of a thin speaker structure,the speaker structure has good mechanical damping characteristics,the thickness is reduced by half compared to the commercially available speakers.Through the impedance tube test experiments to verify the correctness of the thin and light loudspeaker design method,and effectively improve the low frequency absorption characteristics of the shunt loudspeaker structure.In the design and experimental process of thin and light loudspeakers,it is found that when the diaphragm is properly divided vibration is conducive to the improvement of the sound absorption performance of the shunt loudspeaker structure.