In a method and a device for the signal processing in a hearing aid, in which coefficients of a filter for the frequency-dependent amplitude adaptation of an input signal are adapted in accordance with this input signal, the following steps are carried out: Determining coefficients of a compression amplification g.sub.m, which describe a frequency-dependent adaptation of the input signal in accordance with frequency-dependent signal levels of the input signal, determining coefficients of a noise suppression a.sub.m, which describe a frequency-dependent adaptation of the input signal in accordance with interference noises detected in the input signal, and the calculation of the coefficients of the filter (6) c.sub.m out of the coefficients of the compression amplification g.sub.m and the coefficients a.sub.m of the noise suppression. In this, only a single controllable filter is utilised both for the compression amplification as well as for the noise suppression, and a delay time for the filtering of the input signal is kept short.