A listening device for processing an input sound to an output sound according to a user's needs, the listening device comprising • an input transducer for converting an input sound to an electric input signal, and • an output transducer for converting a processed electric output signal to an output sound, • a forward path being defined between the input transducer and the output transducer and comprising a signal processing unit adapted for processing an SPU-input signal originating from the electric input signal in a time-frequency representation comprising successive time frames each comprising a frequency spectrum of the electric input signal in the time frame in question, the signal processing unit defining an input side and an output side of the forward path and comprising o a spectral content modification unit adapted for modifying values of the signal of one or more 'target' frequency regions of the frequency spectrum of a given time frame, thereby providing an improved processed output signal, and • a feedback loop from the output side to the input side comprising a feedback path estimation unit for estimating the effect of acoustic feedback from the output transducer to the input transducer, wherein the feedback path estimation unit is adapted to use the improved processed output signal in the estimation, • CHARACTERIZED IN THAT the spectral content modification unit is configured to substitute spectral content of said 'target' frequency region with spectral content of a 'source' frequency region, or to combine spectral content of said 'target' frequency region with spectral content of a 'source' frequency region, wherein the spectral content modification unit is further adapted to base the modification of spectral content of the SPU-input signal on a distortion measure based on a model of the human auditory system configured to compare two signal segments, a reference signal and a modified signal, and to determine whether the changes introduced in the modified signal are detectable compared to the reference signal. • an input transducer for converting an input sound to an electric input signal, and • an output transducer for converting a processed electric output signal to an output sound, • a forward path being defined between the input transducer and the output transducer and comprising a signal processing unit adapted for processing an SPU-input signal originating from the electric input signal in a time-frequency representation comprising successive time frames each comprising a frequency spectrum of the electric input signal in the time frame in question, the signal processing unit defining an input side and an output side of the forward path and comprising o a spectral content modification unit adapted for modifying values of the signal of one or more 'target' frequency regions of the frequency spectrum of a given time frame, thereby providing an improved processed output signal, and • a feedback loop from the output side to the input side comprising a feedback path estimation unit for estimating the effect of acoustic feedback from the output transducer to the input transducer, wherein the feedback path estimation unit is adapted to use the improved processed output signal in the estimation, • CHARACTERIZED IN THAT the spectral content modification unit is configured to substitute spectral content of said 'target' frequency region with spectral content of a 'source' frequency region, or to combine spectral content of said 'target' frequency region with spectral content of a 'source' frequency region, wherein the spectral content modification unit is further adapted to base the modification of spectral content of the SPU-input signal on a distortion measure based on a model of the human auditory system configured to compare two signal segments, a reference signal and a modified signal, and to determine whether the changes introduced in the modified signal are detectable compared to the reference signal.