Broadband acoustic holography from intensity measurements with a three-dimensional pressure-velocity probe.

Abstract

Near-field acoustic holography requires one or more reference signals corresponding to sound sources to help get the phase of complex pressure on the hologram plane, while broadband acoustic holography from intensity measurements (BAHIM) breaks through this restriction by getting the phase from the quadratic pressure and tangential components of sound intensity. However, in the conventional BAHIM all the sound sources are confined to one side of the hologram plane. In the present paper, by utilizing a three-dimensional pressure-velocity (3D p-u) probe that is composed of one pressure microphone and three orthogonally placed particle velocity sensors, the BAHIM is extended to be applicable to the situation that the disturbing sources exist on the opposite side of the hologram plane. The validity of the extended BAHIM is examined both numerically and experimentally. The results demonstrate that, by using the extended BAHIM, the complex pressure as well as the normal particle velocity on the hologram plane can be measured with a 3D p-u probe without using any reference signal, the pressure radiated by the target source can be extracted from the mixed sound field, and the sound field of interest can be reconstructed effectively.