Filter bank system for a hearing aid, comprising - an analysis filter bank with a plurality of individual filters for decomposing an input signal into sub-band signals, - a processing device for amplifying at least one of the sub-band signals, and - a synthesis filter bank with a plurality of individual filters for combining the processed sub-band signals into an output signal, - the sub-band signals are oversampled in the analysis filter bank, the processing device and the synthesis filter bank with an oversampling factor U and downsampled compared to the input signal with a downsampling factor, characterised in that - the stopband attenuations of the individual filters * of the analysis filter bank are at least as high as a predefined first signal-to-noise ratio increased by a first attenuation value which is a function of the oversampling factor U and the downsampling factor, and/or * of the synthesis filter bank are at least as high as a predefined second signal-to-noise ratio increased by a second attenuation value which is a function of the oversampling factor U, the downsampling factor and the gain of the processing device, and - the magnitude frequency response of the synthesis filter bank is approximately matched to the magnitude frequency response of the analysis filter bank such that - the complex-valued frequency response of the cascade analysis filter bank and synthesis filter bank bypassing the processing device is approximately an all-pass transfer function. - an analysis filter bank with a plurality of individual filters for decomposing an input signal into sub-band signals, - a processing device for amplifying at least one of the sub-band signals, and - a synthesis filter bank with a plurality of individual filters for combining the processed sub-band signals into an output signal, - the sub-band signals are oversampled in the analysis filter bank, the processing device and the synthesis filter bank with an oversampling factor U and downsampled compared to the input signal with a downsampling factor, characterised in that - the stopband attenuations of the individual filters * of the analysis filter bank are at least as high as a predefined first signal-to-noise ratio increased by a first attenuation value which is a function of the oversampling factor U and the downsampling factor, and/or * of the synthesis filter bank are at least as high as a predefined second signal-to-noise ratio increased by a second attenuation value which is a function of the oversampling factor U, the downsampling factor and the gain of the processing device, and * of the analysis filter bank are at least as high as a predefined first signal-to-noise ratio increased by a first attenuation value which is a function of the oversampling factor U and the downsampling factor, and/or * of the synthesis filter bank are at least as high as a predefined second signal-to-noise ratio increased by a second attenuation value which is a function of the oversampling factor U, the downsampling factor and the gain of the processing device, and - the magnitude frequency response of the synthesis filter bank is approximately matched to the magnitude frequency response of the analysis filter bank such that - the complex-valued frequency response of the cascade analysis filter bank and synthesis filter bank bypassing the processing device is approximately an all-pass transfer function.