Hearing aid configured to select a reference microphone

A binaural hearing aid system adapted for being worn by a user, wherein the binaural hearing aid system comprises a first hearing aid and a second hearing aid, each of the first hearing aid and a second hearing aid being adapted for being worn by a user at or in an ear of the user or to be partially or fully implanted in the user's head at an ear of the user, each of the first hearing aid and the second hearing aid comprising

• at least two microphones, providing respective at least two electric input signals representing sound around the user wearing the respective hearing aid;
• a filter bank converting the at least two electric input signals into signals as a function of time and frequency, e.g. represented by complex-valued time-frequency units;
• transceiver circuitry establishing a communication link allowing data to be exchanged between the first hearing aid and the second hearing aid, the data comprising at least one further electric input signal;
• and
• a directional system in communication with the at least two microphones and the transceiver circuitry, the directional being configured to provide a filtered signal in dependence of the at least two electric input signals, the at least one further electric input signal, and beamformer weights;
• wherein the binaural hearing aid system is configured to:
• provide that a direction to a target sound of each of the first hearing aid and the second hearing aid is defined as a target direction;
• select, for each frequency band, one of the at least two microphones of the first hearing aid as a first reference microphone, and provide a first reference input signal for each frequency band,
• wherein the first reference microphone for a given frequency band is adaptively selected based on a logic criterion, wherein the logic criterion comprises a comparison of first estimated acoustic transfer functions, each of the first estimated acoustic transfer functions being indicative of a transfer function between the target direction of the first hearing aid and a respective microphone of the at least two microphones of the first hearing aid, wherein for a given frequency band, the first reference microphone is selected as the microphone exhibiting the largest first acoustic transfer function of the first estimated acoustic transfer functions in the given frequency band;
• and
• select, for each frequency band, one of the at least two microphones of the second hearing aid as a second reference microphone, and provide a second reference input signal for each frequency band,
• wherein the second reference microphone for a given frequency band is adaptively selected based on a logic criterion, wherein the logic criterion comprises a comparison of second estimated acoustic transfer functions, each of the second estimated acoustic transfer functions being indicative of a transfer function between the target direction of the second hearing aid and a respective microphone of the at least two microphones of the second hearing aid, wherein for a given frequency band, the second reference microphone is selected as the microphone exhibiting the largest second acoustic transfer function of the second estimated acoustic transfer functions in the given frequency band.