Several variants of near field acoustic holography (NAH) that do not require measurement areas larger than the source have been proposed. This paper examines and compares two such methods, statistically optimised near field acoustic holography (SONAH) and the Helmholtz equation least squares method (HELS). The HELS method is based on expanding the sound field into spherical harmonics and may therefore be expected to work best for spherical sources; SONAH is based on propagating and evanescent plane waves and may be expected to work best for planar sources. The performance of SONAH and HELS is examined for spherical as well as non-spherical sources.
Main Research Area:
International Conference on Theoretical and Computational Acoustics, 2007