Sound field separation technique for nonplanar sources based on field prediction by using statistically optimized near-field acoustic holography

Abstract

For the sound field of cylindrical or compact sources, the current sound field separation technique (FST) based on statistically optimized near-field acoustic holography (SONAH) uses planar wave for separation, and the effects of different wave functions have not yet been studied. However, the non-conformal problem between the hologram surface and the sound sources commonly has a risk of accuracy reduction. Here, an FST for nonplanar sources based on SONAH is proposed to solve this problem. First, considering that field prediction of near-field acoustic holography will attenuate errors, noise immunity of the FST is effectively improved in a noisy environment by moving the reconstruction surface to the prediction area. Subsequently, the appropriate conformal wave function is determined by combining the shape of the sound source and is substituted into the improved method in the first step to separate the free-field sound pressure. Finally, simulations, experiments using loudspeakers, and a cylindrical experiment platform prove the effectiveness of the proposed method, which can greatly improve the adaptability and reliability of the FST in nonplanar sound sources in mechanical systems.