Patch near-field acoustic holography: The influence of acoustic contributions from outside the source patch

摘要

It is a requirement of conventional Near-field Acoustic Holography that the measurement arearncovers the entire surface of the source. In the case of Patch Near-field Acoustic Holographyrn(patch NAH), the measurement area can be reduced to cover only a specific area of the sourcernwhich is of particular interest (known as the “patch” or “source patch”). The area of the sourcernbeyond this patch is not of interest in the analysis. However, its acoustic output may neverthelessrncontribute to the total sound field in the measurement plane, and influence the reconstructionrnof the field close to the patch. The purpose of this paper is to investigate how the acoustic radiationrnfrom outside the patch area influences the reconstruction of the sound field close to thernsource. The reconstruction is based on simulated measurements of sound pressure and particlernvelocity.rnThe methods used in this paper are the Statistically Optimized NAH (SONAH) and thernEquivalent source Method (ESM), also known as the Wave Superposition Method. Particularrnattention is drawn to how the equivalent sources in the ESM could be distributed in order tornachieve an acceptable reconstruction of the sound field. It has been shown that an acceptable reconstructionrnof the normal velocity can be achieved if the contributions from beyond the patchrnarea are accounted for.