Modified Wideband Acoustical Holography for Improving the Identification of Acoustic Sources at Low Frequencies

Source identification and sound field reconstruction using near-field acoustical holography (NAH) is particularly challenging when the measurement data are relatively fewer than the sources to reconstruct. Fast wideband acoustical holography (WBH) is an inverse solution method based on the compressed sensing theory, which enables the NAH with such sparse measurement and extends its applicable frequency range. WBH usually works well at high frequencies, but it is often unsatisfactory when dealing with low-frequency coherent sources. This work proposes a modified WBH method to improve low-frequency and high-frequency performance substantially. It is developed by combining the conventional WBH and the steepest descent methods in computing the initial source strength values. It contrasts the WBH method using specific initial values for the equivalent sources. The iteration is repeated to ensure that these source strengths are not involved in the threshold filtering process during the iteration process. The simulation and experiment show that the proposed modified WBH substantially improves the reconstruction accuracy of coherent sound sources at low frequencies without degrading the reconstruction performance at mid to high-frequencies.