聚四氟乙烯微孔膜的透声性能实验

为研究微孔薄膜材料的透声性能，搭建了改进的四传声器阻抗管隔声量测试系统，推导了阻抗管中隔声量的传递损失矩阵算法，此算法可以有效地分离隔声管中透射波与二次反射波，使测试结果不受隔声管末端材料吸声性能的影响，与原四传声器算法相比物理意义更明确．对3种微孔薄膜样品进行了实验和分析，结果表明改进的测试方法可以精确地测试样品隔声量，尤其能提高低频段隔声量的测试精度，测试结果重复性优于原方法．

Measurement of Acoustic Performance of PTFE Microporous Membrane

A new method of sound transmission loss measurement using a modified four-microphone impedance tube was proposed in this paper to investigate the microporous membrane＇s acoustic performance. Transmission loss matrix algorithm of the system was conducted with the physical meaning more clear than that of four-micro- phone impedance algorithm. The new algorithm effectively separated the transmission wave from the secondary reflected wave in the impedance tube and ensured the measurement result not to be influenced by absorbent end of the tube. Three types of microporous membrane were studied with new algorithm. The results indicate that the new method can raise the precision and repeatability of the measurement, especially in low frequency.