There is provided a method of controlling a noise cancellation system, the noise cancellation system being for use in a device comprising a speaker for receiving a wanted signal and generating a sound signal therefrom, and the noise cancellation system comprising: a digital filter, for generating a noise cancellation signal from an input signal representative of ambient noise; and an output for applying the noise cancellation signal to the speaker in addition to the wanted signal to generate a sound signal from which the ambient noise has been at least partially cancelled. The method comprises: determining a resonant frequency of the speaker; based on the determined resonant frequency, selecting a set of filter coefficients; and applying the selected set of filter coefficients to the digital filter.