Combining acoustic imaging techniques to localize and identify sources

Abstract

This paper deals with recent advances in acoustic experimental methods and especially acoustic imaging. The paper covers two areas of interest to acousticians. In the first part, it is explained how near-field acoustic holography (NAH) can be extended with beamforming in the near-field, focalization. The combination of the two methods is providing now a source localization solution with a good spatial resolution over the complete frequency range without the burden of measuring a large number of points as would be required if only NAH was used. In the second part of the paper, a method is described that goes one step beyond source localization. It is interesting to locate the noise sources, but from an engineering standpoint it is even more interesting to know the internal sources/forces causing these noise sources. In this part is explained how source localization techniques in conjunction with artificial excitation of the structure can provide information on the internal sources of the structure.

Some research challenges of acoustic camera

“…Mathematical model of the signal on microphone array in near filed scenario depends on the locations of the sound sources, so the near-field beamforming can directly identify locations of acoustic sources and provide acoustic picture in spatial sector of interests (DOAs in far field, became locations in near-filed beamforming). In literature near-field beamforming is also named focalization [18].…”