Nearfield holography for wideband sources

Abstract

Nearfield acoustical holography (NAH), a process developed at the Pennsylvania State University, has proved itself to be a powerful research tool in the study of single-frequency sound sources. A new high-speed data aquisition system has been developed which permits extension of the nearfield acoustical holography technique to the study of wideband noise sources. Using a partially parallel, partially sequential sampling network, near simultaneous sampling is achieved for 256 microphones in the holographic measurement plane, for acoustic frequencies up to 1500 Hz. Special problems encountered during the development of the high-speed data aquisition system are discussed. [Work supported by ONR and NASA.]