METHOD AND APPARATUS FOR CANCELLING VIBRATIONS

Methods and apparatus for cancelling both random and repetitive vibrations in gases, liquids or solids. The invention relies on generating cancelling vibrations (S) for a primary vibration to be nulled (P) by operating at discrete locations in the frequency domain of time samples of the waveform of the primary vibration. The cancelling vibrations required are generated by transforming (at 15) the sensed residual vibrations into a plurality of pairs of components which together define the residual vibrations at a plurality of different locations in the frequency domain, separately modifying (at 17) the independent components and then transforming (at 20) the modified components back into a drive signal for the source (12) of the cancelling vibrations.