Abstract
Feedforward active noise control (ANC) techniques based on an adaptive H 2 algorithm and an adaptive H ∞ algorithm are proposed in this paper. Although fixed H 2 and H ∞ controllers are effective for attenuating broadband random noises and transient noises, their robustness of performance and stability against plant uncertainties or perturbations is often questioned. In the study, the robust problem is resolved by introducing an adaptive compensator based on the normalized least-mean-square (NLMS) algorithm, while on the other hand the merits of the fixed controllers are preserved. The algorithms are implemented by using a floating point digital signal processor (DSP). Extensive experimental investigations justify the effectiveness of the proposed methods in suppressing broadband random noises and transient impact noises in a duct.