Ka. Cunefare et S. Shepard, THE ACTIVE CONTROL OF POINT ACOUSTIC SOURCES IN A HALF-SPACE, The Journal of the Acoustical Society of America, 93(5), 1993, pp. 2732-2739
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.