基于二阶循环统计量的近场声全息试验研究

Experimental study on near-field acoustic holography based on the second-order cyclic statistics

传统近场声全息技术的重建结果不能准确反映循环平稳声场的调制特性。因此,利用循环自相关函数的解调性能来提取声场的特征循环频率,然后通过循环维纳-辛钦关系来获取循环谱密度,将循环谱密度取代声压谱作为平面近场声全息的声场重建物理量。试验研究表明,此方法可准确提取循环平稳声场的特征频率,重建结果可清晰直观的突出声场的本质特性。

The conventional near-field acoustic holography technology can not mirror exactly modulation characteristics of cyclostationary sound field through the reconstructed results.So the demodulation ability of the cyclic autocorrelation function was used to extract the characteristic cyclic frequency.The cyclic spectrum density（CSD） was then obtained through the cyclic Wiener-Khinchin relation,and the CSD was adopted as reconstructed physical quantity in planar near-field acoustic holography instead of the spectrum of pressure.The experiment researches show that the characteristic frequency of cyclostationary sound field can be extracted accurately and its essential characteristics can be observed directly from the reconstructed results.