ASA 124th Meeting New Orleans 1992 October

4aSA14. Active noise control applied to extended sources in a half-space.

Steve Shepard

Kenneth A. Cunefare

George W. Woodruff School of Mech. Eng., Georgia Inst. of Technol., Atlanta, GA 30332-0405

Much of the theoretical and computational work to date on the active noise control of extended structures generally considers the subject body to be in free-space. In practice, most structures of interest are located in close proximity to a bounding plane, such as the ground surface. The research presented in this paper extends the existing body of work related to the active control of noise radiated by extended three-dimensional structures to include the presence of a reflective infinite plane, that is, within a half-space. As with point sources, when the structure to be controlled is within one wavelength of the reflective plane, be it rigid or pressure release, the plane can impact the control versus control under free-field conditions. The research exploits the method of images to adapt the existing boundary element techniques for active noise control analysis of extended structures.