传声器次声段灵敏度校准的误差机理研究

Study on the calibration error mechanism of the infrasound sensitivity of microphones

次声波广泛存在于自然界与人类活动中,由于次声波具有穿透能力强、衰减小等特点,隔离和消除十分困难,对次声的监测防护与利用成为人们关注的焦点。次声波的定量研究依托传声器的测量实现,对传声器的灵敏度原级校准是保证测量精度的前提。该文基于活塞发生器校准原理下的压力泄漏与热传导耦合衰减模型,在COMSOL多物理场仿真软件中对校准腔和传声器后腔内的声场特征进行了数值仿真。创新性地提出了模型比较法,准确量化了次声段校准核心的泄漏、热传导独立与耦合修正量,验证并揭示了声压泄漏与热传导损失的幅值与相位变化机理。进一步地对传声器的次声段灵敏度校准过程进行了联合数值模拟,仿真结果表明,内外均压校准声场下传声器灵敏度的幅相频响应存在明显差异,但与校准腔内的泄漏与热传导效应无关。基于搭建的活塞发生器原级校准平台对传声器系统进行了原级校准,通过实验手段初步揭示了内外均压校准机制下传声器幅值灵敏度与相位灵敏度的显著差异。

Infrasound widely exists in nature and human activities.Due to the higher penetration and lower attenuation of infrasound,it is difficult to isolate and eliminate it,which has become the focus of attention for monitoring,protection and utilization of infrasound.The quantitative research of infrasound is realized by the measurement of microphones,and the primary calibration of microphone sensitivity is the prerequisite to ensure the measurement accuracy.This paper was based on the pressure leakage and heat conduction coupling attenuation model under the calibration principle of pistonphone.The numerical simulation of the sound field characteristics in the calibration chamber and the microphone back-cavity was carried out,which was based on COMSOL multi-physical simulation software.The model comparison method was innovatively proposed,which was the key to quantify the independent and coupling corrections of leakage and heat conduction accurately in the infrasound calibration.And the amplitude and phase variation mechanism of pressure leakage and heat conduction loss was verified and revealed.Furthermore,joint simulation of the calibration process was carried out.The simulation results show that the amplitude and phase frequency response of microphone sensitivity is significantly different in the ventin-field and vent-outfield,but it is not related to leakage and heat conduction in the calibration chamber.The primary calibration of the microphone system was carried out based on the built primary calibration platform of the pistonphone.The significant difference between the amplitude sensitivity and phase sensitivity of microphone for ventinfield and ventoutfield calibration mechanisms were revealed preliminarily by experimental means.