Research on novel combined near-field acoustic holography using extrapolation and sparse method and its application conditions

In the field of sound source identification, near-field acoustic holography (NAH) based on the boundary element method (BEM) is a powerful technique. However, its performance is limited by the number of measurement points and the size of the holographic aperture. Although patch NAH and compressed-sensing-based NAH can effectively improve reconstruction accuracy when the number of measurement points is limited, the reconstruction accuracy cannot be guaranteed when the number of measurement points or the holographic aperture is excessively small. In this study, a novel combined NAH is proposed. The sound field extrapolation method is used to expand the holographic aperture, and the sparse method is employed to reconstruct the surface velocity of the sound source. Numerical simulations and experimental results demonstrate the effectiveness of the proposed method. The results demonstrate that when the holographic surface uses regularly sampling and the extrapolation aperture is extrapolated by two element spacings along the transverse and longitudinal directions of the initial holographic aperture, the proposed method enhances reconstruction accuracy compared to standalone sparse BEM-NAH.