A Comparison of Near-Field Acoustic Error Sensing Strategies for the Active Control of Harmonic Free Field Sound Radiation

Abstract

A theoretical comparison of a number of near-field acoustic error sensing strategies is undertaken for active control of harmonic free-field sound radiation. Error sensing strategies investigated include the minimization of acoustic potential energy density, acoustic kinetic energy density, total acoustic energy density and mean active sound intensity at a point and the minimization of the sum of each cost function at a number of points in the near field. The error sensing strategies are analyzed for harmonic sound fields radiated by a monopole primary source and a dipole-like pair of primary sources. The control source is a monopole radiating at the same frequency and the criterion used to assess the error sensing strategies is the minimization of the total radiated acoustic power. It was found that the most appropriate near-field acoustic error sensing strategy for the active control of harmonic free-field sound radiation is minimizing the sum of the weighted mean active intensity in the direction normal to the surface surrounding all the primary and control sources. © 1998 Academic Press.