Determination of effective secondary source locations for active noise control

Abstract

A numerical method for determining effective secondary source locations for active control of interior sound fields has been investigated. The method uses intermediate results from an indirect boundary element simulation of a sound field to determine effective boundary locations for secondary sources. In the indirect boundary element method (IBEM), an interior sound field is simulated by replacing the physical boundaries with a fictitious source distribution that is determined from the geometry, the properties of the physical boundaries, and the primary source location(s). Locations of high fictitious source strength, as determined by the IBEM, are found to be particularly effective locations for secondary sources that are components in three dimensional active noise control systems. Numerical results for simple geometries are in agreement with previous experimental results [Elliott etal., J. Sound Vib. 117, 35–58 (1987)], and numerical predictions of active noise control using the proposed method for locating secondary sources resulted in sound pressure level reductions of more than 20 dB in reverberant and semi-reverberant spaces. The results obtained suggest that the method has significant potential for efficiently locating effective secondary sources for a variety of active noise control applications.