Active control of stationary random sound fields

Nelson, P. A., Hammond, J. K., Joseph, P. and Elliott, S. J. (1990) Active control of stationary random sound fields. Journal of the Acoustical Society of America, 87 (3), 963-975. (doi:10.1121/1.399432).

Abstract

Previous work on the active control of sound has mostly used frequency domain formulations in order to establish the physical limitations of active methods. While entirely adequate for the prediction of the performance of active control systems designed to deal with deterministic primary fields, these methods cannot necessarily be applied in cases where the primary excitation is stationary random in nature. The application of frequency domain techniques often yields results for the optimal control strategy that require the secondary sources to act noncausally with respect to the primary sources. The work described here illustrates classical time domain methods for determining the performance limits of active noise control systems that are constrained to act causally. The first example considered is the minimization of the mean-squared acoustic pressure at a position in the field of a point monopole primary source by the introduction of a point monopole secondary source. The primary source radiates a stationary random signal and the secondary source is constrained to act causally with respect to the primary source. The active control of low-frequency random sound in enclosures is then addressed and the classical Wiener theory extended in order to deal with problems involving the minimization of multiple errors. The active control of a one-dimensional enclosed sound field is presented as a simple example. This theory is also used in presenting a third example that consists of a primary/secondary source pair radiating in a free field. The minimum acoustic power output of the source combination is calculated when the primary source radiates random sound and the secondary source is again constrained to act causally with respect to the primary source.

This record has no associated files available for download.

Contributors

Author: P. A. Nelson

Download statistics