The various equivalent source methods for noise source visualization can generally be categorized according to two factors: the complexity of the model (order of the sources) and the flexibility of the model (sources at fixed or unfixed location). The models used in the present work comprised: (i) a large number of low-order sources at fixed locations (low model order, low flexibility), and (ii) a high model order series at an unfixed location (high model order, high flexibility). With reference to case (i), a new equivalent source procedure based on a monopole distribution at fixed locations, which is referred to as wideband holography was recently developed by Hald. By using this method the balance between the model accuracy and the sparsity of the underdetermined system can be optimized. For case (ii), a higher order series at unfixed locations was recently proposed by Liu and Bolton. The unfixed location model was found to offer better accuracy of noise source location estimation compared with the more usual fixed-location model. In the present work, these two methods were used to reconstruct the noise sources of a loudspeaker cabinet. The measurement were conducted using an eighteen channel irregular array. A comparison of the reconstruction result from these two method help to highlight the strengths and weakness of each procedure.
Acoustical holography, Equivalent source method, Wideband acoustical holography, Noise source identification
Acoustics and Noise Control
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