Research on the cyclostationary nearfield acoustic holography based on boundary element method

Cyclostationary sound field is a special kind of nonstationary sound field,in which pressure signal is modulated seriously and sidebands exist in its spectrum.The reconstructed sound field can't figure the cyclostationary features in original Nearfield Acoustic Holography (NAH) procedure.On the basis of planar cyclostationary NAH,the cyclostationary NAH based on boundary element method is proposed which can be utilized to radiators with complicated surface in cyclostationary sound field.Replacing the Fourier's transform with the second-order cyclic statistics,the Cyclic Spectral Density (CSD) functions is used as the reconstructed physical quantity in the proposed NAH technique, instead of the spectrum or power spectral density of pressure signal.By virtue of the demodulation ability of CSD function,the reconstructed CSD holograph can effectively express the information of modulating and carrier wave solely. The simulation and experiment illustrate that the validity and accuracy of this cyclostationary NAH technique satisfy the request of engineering.