2011 Volume 6 Issue 1 Pages 107-118
This paper is concerned with an active noise control for an enclosed sound field. It is the purpose of this paper to present an active wave control method of a three dimensional rectangular cavity and to clarify fundamental properties of the control system. Firstly, a transfer matrix method for the target system is newly introduced to describe the wave dynamics in the enclosure. This is followed by the derivation of feedforward control laws for absorbing reflected waves or eliminating transmitted waves. In the proposed method, the control laws are including the modal actuation scheme for uncontrolled direction. Then, from a viewpoint of numerical analyses, basic properties of the proposed method are verified. It is found that the transmitted wave eliminating control enables the generation of silent zone, and the reflected wave absorbing control enables the inactivation of acoustical modes in the controlled direction.