RESEARCH AND APPLICATION ON IMAGING THE PLANAR PATCH ACOUSTIC FIELD BASED ON THE LEAST SQUARE METHOD

The nearfield acoustic holography (NAH) is efficient and accurate for visualizing the acoustic field. Patch NAH was developed for analyzing the interested part of the acoustic field excited by a large-scale structure. The Least Square Method (LSM) is a kind of patch NAH method, which uses a series of elemental waves to approximately approach to the real acoustic field including the sound pressure and particle velocity. Three kinds of LSMs are investigated whose basic waves are planar elemental wave, spherical waves on one origin and distributed simple monopoles, respectively. All of these methods can be applied to analyze patch acoustic field. The reconstruction accuracies due to different methods are compared in the numerical experiments. The effects of numerical parameters on the reconstruction accuracy are researched, including three critical parameters such as the overlap area, measurement distance and space of neighboring measurement points. The comparisons on the LSMs in the patch acoustic field reconstruction will give some suggestions to choose the suitable method and appropriate parameters to investigate the acoustic field.