For the noise reduction of an audio signal generated by stereo-demultiplexing of a frequency-modulated stereo multiplex signal (S_FM(t)) a filtering within the signal path to generate the stereo difference signal (u_d(t)) is performed that determines a weight with which the upper sideband (u_d,u(t)) and the lower sideband (u_d,l(t)) of the amplitude modulated stereo-difference signal are weighted with different weighting factors that are dependent on the frequency.