电动式换能器声源级起伏改善实验研究

Experimental research on improving source level fluctuation ofmoving coil projector

电动式换能器由于存在内部声腔,导致辐射面上的负载在频域上出现极值,使得电动式换能器的声源级响应出现起伏,给电动式换能器在宽带噪声模拟领域的应用带来了挑战。依据电动式换能器含有声腔的等效电路分析结果,针对无声腔、有声腔、在声腔底部设置吸声棉和在声腔内充入氦气4种情况,使用加速度计测试了辐射面的输出振速,归算出声源级曲线并加以比较。实验结果验证了声腔谐振导致电动式换能器频响曲线出现起伏;在声腔内充入特性阻抗小的气体可有效地将声腔的谐振频率调节至工作频段以外,从而实现电动式换能器在质量控制区平坦的响应输出。

Due to the acoustic cavity in moving coil projector,the load on the radiation surface has extreme values in the frequency domain,which makes the source level response of the projectorfluctuate.It is harmful to the application of the projector in thefield of broadband noise simulation.Base on the analysis result of the equivalent circuit of moving coil projector containing the acoustic cavity,experimental research is carried out in this paper.The output vibration velocity on the radiation surface was tested with the accelerometer for the four cases:without acoustic cavity,with acoustic cavity,setting sound-absorbing cotton at the bottom of the acoustic cavity,andfilling helium gas in the acoustic cavity.Then the source level curves for the four cases are calculated and compared.The experimental results verify that the resonance of the acoustic cavity can lead to source levelfluctuations;filling low characteristic impedance gas in the acoustic cavity can effectively improve thefluctuation of the source level in the quality control area.