Active noise control - a review of control-related problems

Active noise control is a research area, where both
acoustic and control related problems influence success of applications. The aim
of the paper is to address the control aspects. After introducing active noise
control in general, the fundamental state of the art is presented. The possible
control techniques are discussed. Premises for the choice of feedforward,
feedback and combined architectures are summarised. Single-channel and
multi-channel systems are confronted. Benefits and drawbacks of continuous-time
and discrete-time approaches are emphasised. Fixed-parameter and adaptive
control systems are referenced. General control system requirements are
formulated. Fundamental performance limitations are explained. Various control
problem formulations including cost functions and constraints are presented for
an exemplary structure.