A hearing assistance system calibrates a noise reduction system of a hearing assistance device. The system comprises a hearing assistance device, and an auxiliary device. The hearing assistance device comprises a multitude of input units, and a multi-channel beamformer filtering unit configured to determine filter weights for a beamformed signal. The system further comprises a user interface for activating a calibration mode. The auxiliary device comprises an output transducer for converting an electric calibration signal to an acoustic calibration sound signal. The system is configured to estimate a look vector for a target signal originating from a target signal source located at a specific location relative to the user based on the acoustic calibration sound signal.