Obtaining the complex pressure field at the hologram surface for use in near-field acoustical holography when pressure and in-plane velocities are measured

Acoustical-based imaging techniques have found merit in determining the behavior of vibrating structures. These techniques are commonly used in numerous applications to obtain detailed noise source information and energy distributions on source surfaces. Source reconstructions using near-field acoustical holography NAH are reliant upon accurate measurement of the pressure field at the hologram surface. For complex acoustic fields this requires fine spatial resolution and therefore demands large microphone arrays. In this paper, an interpolation method is developed for obtaining the complex pressure field at the hologram surface from pressure and velocity measurements. Because particle velocity measurements provide directional information, a more accurate characterization of the pressure field with fewer measurement locations is obtained. The processing technique presented does not relate directly to the holographic reconstruction itself. However, the interpolation scheme presented serves as a preprocessing step before a NAH algorithm is applied. The presentation and validation of the interpolation scheme is the major focus of the paper. An analytical comparison of NAH reconstructions from traditional pressure measurements to reconstructions using the preprocessed pressure and velocity measurements is presented. A vibrating plate and cylinder are considered as test cases to validate the analytical results. © 2006 Acoustical Society of America. DOI: 10.1121/1.2159427