A method of operating a hearing aid system with virtually zero delay and phase distortion. The invention also provides a hearing aid system (100) adapted for carrying out such a method.

A method of operating a hearing aid system with virtually zero delay and phase distortion. The invention also provides a hearing aid system (100) adapted for carrying out such a method.

A filter apparatus (100) having a signal input (101) to which an input signal is applied which contains a useful component and a noise component, a fast signal path (102) and a slow signal path (103) arranged in parallel therewith. The fast signal path and the slow signal path are coupled to the signal input. The fast signal path contains a filter in order to prompt fast filtering of the input signal. The slow signal path contains a filter in order to prompt slow filtering of the input signal. An output of the slow signal path is coupled to the fast signal path by means of a signal line (106). A signal output (104) which is coupled to the fast signal path has an output signal applied to it which essentially contains useful components of the input signal.