Abstract: A noise cancellation filter structure for a noise cancellation enabled audio device, in particular headphone, comprises a noise input for receiving a noise signal and a filter output for providing a filter output signal. A first noise filter produces a first filter signal by filtering the noise signal and a second noise filter produces a second filter signal by filtering the noise signal. The second noise filter has a frequency response with a non-minimum-phase, in particular maximum-phase. A combiner is configured to provide the filter output signal based on a linear combination of the first filter signal and the second filter signal.

Abstract: A noise cancellation system for a noise cancellation enabled audio device comprises a first noise filter and a second noise filter, each being designed to process a noise signal, a combiner and an adaptation engine. The first noise filter has a first fixed frequency response matched to a high leakage condition of the audio device. The second noise filter has a second fixed frequency response matched to a low leakage condition of the audio device. The combiner is configured to provide a compensation signal based on a combination of an output of the first noise filter amplified with a first adjustable gain factor and an output of the second noise filter amplified with a second adjustable gain factor. The adaptation engine is configured to estimate a leakage condition of the audio device based on an error noise signal and to adjust at least one of the first and the second adjustable gain factors based on the estimated leakage condition.