均压孔结构对p-p声强探头精度的影响

Effect of Pressure-equalization Vent on Accuracy of p-p Sound Intensity Probe

传声器均压孔在平衡腔体内外大气静压的同时,也为其建立了声学低频通道,因而影响到传声器的低频相位特性。基于传声器等效声学模型,对均压孔暴露和未暴露外部测试声场两种状态下的声强探头相位失配误差进行了讨论,并深入分析了驻波声场下均压孔结构对声强探头测试精度的影响。指出具有普通均压孔结构的声强探头通过传递函数修正完全可以达到IEC1043对I级声强探头在驻波声场中的测试精度要求。分析模型和结论的有效性最终通过试验得到了验证。

The purpose of pressure-equalization vent is to prevent the diaphragm from bulging if there is a change in atmospheric pressure,so it can affect low frequency characteristic of microphone.Based on the equivalent acoustic models,the phase mismatching characteristic of sound intensity probe is analyzed when vents are exposed to the acoustic field or not.Then the effect of pressure-equalization vents on accuracy of p-p sound intensity probe under a standing wave field is discussed in detail.It is pointed out that sound intensity probes with common microphones can satisfy the accuracy requirement of IEC1043 if the phase mismatch errors are corrected by transfer function method.At last,the analysis models and conclusions are tested through experimental results.