Active noise control: a marriage of acoustics and control

In a response to a growing demand for environments of 70 dB or less noise levels, many industrial sectors have focused their attention on the development of quality products with some form of noise control (cancellation) system. Automotive manufacturers, aircraft designers; engine manufacturers; appliance industries; producers of heating, ventilating, and air conditioning systems, etc. all have been involved in formulation and development of noise control mechanisms for their products. Active noise control (ANC) has proven to be the most effective technology, especially for low frequency excitations that the human is more sensitive to. Active noise control requires integration of control theory, acoustic, on-line system identification, and signal processing. Thus, ANC is a cross-disciplinary subject that requires expertise from several areas, especially control and acoustics. The author´s research activity in this area over the past eight years has gone through many challenges in order to develop ANC systems that have been feasible and accurate from both control and acoustics viewpoints. This paper summarizes lessons learned from the marriage of acoustics and control, and provides an overview of progresses made in ANC by investigating active noise cancellation from a control point of view. This has been in contrast to almost all other approaches taken from acoustics, modal analysis, and/or adaptive signal processing viewpoint.