Although active noise control by means of destructive interference of sound waves has been studied for several decades, inherent difficulties associated with the method have precluded its use on a large scale and 3-dimensional sources. The lack of success for large noise sources stems from a lack of knowledge of how the surface acoustic intensity of the noise source is altered with the addition of multiple active sources. This project removes this limitation by developing a research tool that uses sound intensity prediction and optimization programs. For a given noise source, the tool provides the guidelines for choosing the optimum number and position of active sources to give the largest sound power reduction possible. Recent development of affordable adaptive control systems using solid state electronics makes it possible to use active noise control as a feasible alternative to more conventional noise control treatments. The project's analysis is supplemented by an experimental activity which culminates with the demonstration of the active control method on a large turbo-machine. ***
