Optimum active noise control at the source—A boundary element technique

Abstract

The authors have developed a numerical technique to determine the optimum magnitude and phase at which to drive active noise control sources to achieve the best possible reduction in the total radiated power from a noise source/control source combination. Both the noise source and the control source(s) have finite areas, and are assumed to be in an infinite, unbounded domain. Use of the boundary element method leads to a quadratic expression for the total radiated power formulated in terms of the surface velocity distribution on the noise source and on the control source(s). This quadratic power expression, formulated at the surface, represents the basis for the technique. Treating the velocities on the control sources as unknowns leads to a system of algebraic equations, the solution of which yields the global minimum for the radiated power, the best possible reduction. Applications of the technique to numerical models of a sphere and of a rectangular box demonstrate the mechanics of active noise control on extended, three-dimensional radiators.