Adaptive active control of free space acoustic noise

Abstract

This paper concerns adaptive active control of acoustic noise in free space. Traditional adaptive active noise control algorithms are efficient in acoustic ducts; however, they are very unstable and sensitive when being used in free space. An efficient adaptive active noise control algorithm for free space noise is derived based on a root locus analysis on the adaptation process performed in adaptive active noise control. The traditional algorithm and the proposed algorithm are fully implemented by using a high performance embedded controller. The controller is then used for active control of acoustic noise in a duct and, also, in free space. Different experiments show that the traditional active noise control algorithm is not stable when the setup is used in free space. However, the proposed algorithm is stable and converges at a high convergence rate until reaching steady state conditions.