Adaptive FeedfolWard algorithms have been successfully applied in the active
control of sound and vibrations~ Current approaches, such as the Filtered-X Least Mean
Square algorithm, are limited in adaptability and applicability by the computationally
intensive system identification process. The Time Average approach is a technique that
promises to be a major advance in the active control of sound and vibration. This
approach is based on statistical estimates of the error signals, and does not require having
previous knowledge of the system. A new minimization algorithm has been developed,
which enhances the performance of the Time Average controllers. A new technique to
estimate the cost function is also presented. This technique is called the Real Time Cost
Function Evaluation method. Based upon these new controller design concepts, single
channel and multi-channel controllers were developed and experimentally tested. The
experiments included control of a harmonically excited, simply supported beam, and the
control of inlet tonal noise radiated from a JT1SD-l turbofan engine.
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