Active Noise Control

In active noise control an artificially-generated secondary acoustic field is used to interfere destructively with the unwanted sound field. This book deals with the control engineering of generating this secondary field. This technique has uses in suppressing machinery noise in particular.

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The prospect of the active control of noise has intrigued, and frustrated, scientists and engineers in many countries for over five decades. The basic idea is relatively simple: to artificially generate a secondary acoustic field that destructively interferes with the field produced by the unwanted sound. However, the limitations of the available electronic technology have restricted practical realization to a few simple applications. With the development of flexible and cheap digital signal processing devices, capable of processing signals within the audio range, there has been a resurgence in interest in the theory and practice of developing Active Noise Control (ANC) systems. Further, the flexibility of these devices allows the development to concentrate on the design procedure and correspondingly control algorithms, rather than the acoustic properties of the arrangements. This book provides a principled introduction to the design of ANC systems from the perspective of control engineering. The approach allows the designer to predict the performance of the system in advance and reduces the empirical aspect of many previous approaches.
The use of control engineering methods allows the progressive development of various control techniques, from fixed digital control to self-tuning adaptive control, to be realized within a single coherent framework.