Adaptive active noise control in free space

This paper develops a reliable methodology for active control of acoustic noise in free space. The core of this paper consists of a root locus analysis on the adaptation process performed in active noise control. Based on this analysis, a novel active noise control algorithm is derived. This algorithm is fully implemented in an experimental setup. Different experiments with this setup 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 the noise level is reduced by 15 dB in steady-state conditions.