THE ACTIVE CONTROL OF POINT ACOUSTIC SOURCES IN A HALF-SPACE

Analysis of active noise control applications generally neglect the pr esence of nearby reflective surfaces, such as a ground plane. The rese arch presented in this paper examines the impact of the presence of a nearby reflective plane on the active control of sound radiated by a n umber of point sources. It is shown that when the sources to be contro lled are within one wavelength of the reflective plane, be it rigid or pressure release, that the plane can significantly impact the control versus control under free-field conditions with the same source separ ations. The orientation of the noise sources and the control sources w ith respect to each other and to the plane also significantly influenc es the control. For sources more than one wavelength away from the ref lective plane, the use of the simpler free-space analysis yields accep table results as compared to using the more complex half-space analysi s.