声腔对电动式换能器工作特性的影响

The influence of acoustic cavity on operating characteristics of electrodynamic transducer

传统的电动式换能器设计理论中,未考虑压力补偿系统等声腔结构对声学性能的影响,声源级理论设计结果与实测结果存在较大差别。研究中将电动式换能器内部的三段气腔视为突变截面声腔结构,给出了声腔的四端网络等效电路,将其作为辐射面的负载添加到电动式换能器的传统等效电路中,获得了电动式换能器改进的等效电路。基于改进的等效电路求解了带有声腔结构的电动式换能器声源级曲线,该曲线与有限元仿真分析结果基本一致,验证了该改进的等效电路在预报电动式换能器声源级方面的正确性。基于该等效电路研究了声腔的结构尺寸、末端声学边界及腔内气体声学参数对声源级起伏特征的影响。结果显示,在声腔末端敷设吸声材料或在声腔内充入特性阻抗较小的气体对于抑制或消除声源级起伏具有明显作用。

The influence of acoustic cavity structure on the acoustic performance of electrodynamic transducer is not considered in traditional design theory.It leads to a big difference between the theoretical design results and the measured results.In the research,the three-segment air cavity inside electrodynamic transducer is regarded as the abrupt cross-section acoustic cavity,the equivalent circuit of the acoustic cavity is added to the traditional equivalent circuit of electrodynamic transducer.Then the improved equivalent circuit of electrodynamic transducer is obtained.Based on the equivalent circuit,the source level with acoustic cavity structure is solved,and the source level with acoustic cavity structure is also simulated by ANSYS software.The results show that the two source level curves are basically the same,which verifies that the improved equivalent circuit is correct in predicting the source level of electrodynamic transducer.The effects of acoustic cavity structure size,end acoustic boundary and cavity gas acoustic parameters on the characteristics of source level are studied.The results show that laying the sound-absorbing material at the end of the acoustic cavity or filling the acoustic cavity with a gas with low characteristic impedance has a significant effect on suppressing or eliminating the fluctuation of source level.