Holographic reconstruction of active sources in three dimensional enclosures

Abstract

Near-field acoustic holography (NAH) is applied to reconstruct an exterior sound field, as well as an interior sound field. A numerical method is employed to reconstruct the interior sound field of an arbitrary shaped enclosure. Reconstructed sound fields are usually used in identifying noise sources. However, until now, it has not been thoroughly verified whether the reconstructed sound field of an interior also shows source distributions. Interior sound fields have been reconstructed without any thought given to this question. In contrast to an exterior sound field, reflections are added to an interior sound field and therefore, the reconstructed sound field may misrepresent the source distribution. This paper addresses a way to solve this problem. A measurement method is proposed in order to distinguish between reflections and direct radiation from noise sources.