An audio system for an ear mountable playback device comprises a compensation filter configured to generate a third compensation signal by applying filter operations to an audio signal, and an error compensation unit configured to generate a compensated error signal on the basis of the third compensation signal and a disturbed audio signal from an error microphone. The audio system further comprises a first noise filter configured to be adapted based on the compensated error signal, and a detection unit configured to estimate the acoustic leakage condition on the basis of the first noise filter or of the disturbed audio signal and an audio output signal. The compensation filter is configured to be adapted based on the acoustic leakage condition.