Concurrent signal paths going pass a hearing aid bring about interferences in the auditory canal. These interferences are compensated by estimating an interfering signal from the input signal disturbed by interference from a microphone and applying to the interfering signal a transfer function, with which the concurrent acoustic signal path is simulated, thereby forming an interfering output signal, and combining a usable output signal from a signal-processing device with the interfering output signal. In this way, a noise suppression by directional microphone switching configurations can be made possible when concurrent signal paths do not make such directional microphone switching possible by conventional approaches.