Fast algorithms in active noise or vibration control

Algorithms are presented for active cancellation of acoustic or mechanical fields with sinusoidal components. The first method is an efficient but not very fast algorithm using Fourier transforms. Experimental results on a multidimensional, multifrequency stationary mechanical problem are given. An adaptive algorithm is presented for cancellation of nonstationary fields with components that are known sinusoids, not necessary harmonic with each other, having magnitude or phase that can be slowly varying. The proposed method does not need synchronous sampling. An antiphase field is produced by the asynchronous synthesis and the updating of each sinusoidal component using iterative formulation and a very simple algorithm. Experimental results are given