基于分流电路调控的宽低频吸隔声机理研究

针对含分流电路的扬声器结构，本文研究了基于频率自适应概念扩宽吸隔声频带的理论机理. 针对扬声器隔声结构模型，揭示了在声波频率和分流电路电感所构成参数空间中存在的高隔声量轨迹，进而设计出控制电路使等效电感参数可以自适应追踪高隔声量轨迹，结果表明在低频区域的隔声带宽获得了显著扩展，将不同工作频率的自适应隔声结构组合可以进一步扩宽隔声频带. 针对扬声器吸声结构模型，发现在频率-电感参数空间同样存在高吸声轨迹，通过设计控制电路自适应追踪高吸声轨迹可以扩宽吸声频带，此外研究了扬声器与微穿孔板构成的复合吸声结构，数值结果表明在自适应吸声与微孔吸声机理的共同作用下吸声频带可被进一步扩宽。本研究为扩展扬声器结构吸隔声频带提供了新的思路，为下一步工程应用设计奠定了理论基础. 

Broadband Low-Frequency Sound Isolation and Absorption Mechan-ism Based on Shunting Circuit Regulation

Considering the structure of loudspeaker with shunting circuits, a new mechanism was proposed to widen the frequency bandwidth of sound absorption and isolation based on the concept of adaptive modulation. Firstly, a suitable loudspeaker structure for broadband and low-frequency sound insulation was studied. The analysis result shows that, in the two-dimensional space parameterized by sound frequency and inductance in shunting circuits, there a trajectory with high sound transmission loss exists, being of advantage to determine a specific profile of the frequency-inductance relationship. According to the analysis result, a shunting circuit was designed, making the frequency-dependent inductance adaptively trace the high sound transmission loss trajectory. The practical experiment results show that, the sound insulation bandwidth can be significantly expanded in the low frequency region, and the bandwidth can be further broadened by combining the adaptive structures with different operating frequency. And then a suitable loudspeaker structure for sound absorption was also studied. The result shows that, there is a similar high sound absorption trajectory existing in the frequency-inductance parameter space. The absorption bandwidth can be broadened by designing a control circuit to adaptively trace the high sound absorption trajectory. Finally, combining an absorptive loudspeaker with micro-perforated plates, a composite structure was studied. The Simulation results show that, the sound absorption bandwidth can be further broadened due to the action of both adaptive circuits and small holes. The study achievement provide a new mechanism for widening the sound absorption and insulation bandwidth of the loudspeaker structure, and is potentially useful in noise control engineering.