A hearing aid adapted for being located in an operational position at or in or behind an ear or fully or partially implanted in the head of a user, the hearing aid comprising • first and second microphones ( M BTE1, M BTE2) for converting an input sound to first IN 1 and second IN 2 electric input signals, respectively, • an adaptive beam former filtering unit for providing a resulting beamformed signal Y BF, based on said first and second electric input signals, the adaptive beam former filtering unit comprising, ∘ a first memory comprising a first set of complex frequency dependent weighting parameters W 11 (k), W 12 (k) representing a first beam pattern, where k is a frequency index, k=1, 2,..., K, ∘ a second memory comprising a second set of complex frequency dependent weighting parameters W 21 (k), W 22 (k) representing a second beam pattern, ▪ where said first and second sets of weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), respectively, are predetermined and possibly updated during operation of the hearing aid, ∘ an adaptive beam former processing unit for providing an adaptively determined adaptation parameter β(k) representing an adaptive beam pattern configured to attenuate unwanted noise as much as possible under the constraint that sound from a target direction is essentially unaltered, and ∘ a resulting beam former for providing said resulting beamformed signal Y BF based on said first and second electric input signals IN 1 and IN 2, said first and second sets of complex frequency dependent weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), and said resulting complex, frequency dependent adaptation parameter β(k), where β(k) is determined as β k = 〈 C 2 * C 1 〉 〈 | C 2 | 2 〉 + c, where * denotes the complex conjugation and 〈·〉 denotes the statistical expectation operator, and c is a constant, wherein said adaptive beam former filtering unit comprises a smoothing unit for implementing said statistical expectation operator by smoothing the complex expression C 2 *·C 1 and the real expression |C 2 | 2 over time, and wherein the smoothing unit is configured to provide that attack and release time constants involved in the smoothing of the complex expression C 2 *·C 1 and the real expression |C 2 | 2 are adaptively determined. • first and second microphones ( M BTE1, M BTE2) for converting an input sound to first IN 1 and second IN 2 electric input signals, respectively, • an adaptive beam former filtering unit for providing a resulting beamformed signal Y BF, based on said first and second electric input signals, the adaptive beam former filtering unit comprising, ∘ a first memory comprising a first set of complex frequency dependent weighting parameters W 11 (k), W 12 (k) representing a first beam pattern, where k is a frequency index, k=1, 2,..., K, ∘ a second memory comprising a second set of complex frequency dependent weighting parameters W 21 (k), W 22 (k) representing a second beam pattern, ▪ where said first and second sets of weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), respectively, are predetermined and possibly updated during operation of the hearing aid, ∘ an adaptive beam former processing unit for providing an adaptively determined adaptation parameter β(k) representing an adaptive beam pattern configured to attenuate unwanted noise as much as possible under the constraint that sound from a target direction is essentially unaltered, and ∘ a resulting beam former for providing said resulting beamformed signal Y BF based on said first and second electric input signals IN 1 and IN 2, said first and second sets of complex frequency dependent weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), and said resulting complex, frequency dependent adaptation parameter β(k), where β(k) is determined as β k = 〈 C 2 * C 1 〉 〈 | C 2 | 2 〉 + c, where * denotes the complex conjugation and 〈·〉 denotes the statistical expectation operator, and c is a constant, ∘ a first memory comprising a first set of complex frequency dependent weighting parameters W 11 (k), W 12 (k) representing a first beam pattern, where k is a frequency index, k=1, 2,..., K, ∘ a second memory comprising a second set of complex frequency dependent weighting parameters W 21 (k), W 22 (k) representing a second beam pattern, ▪ where said first and second sets of weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), respectively, are predetermined and possibly updated during operation of the hearing aid, ▪ where said first and second sets of weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), respectively, are predetermined and possibly updated during operation of the hearing aid, ∘ an adaptive beam former processing unit for providing an adaptively determined adaptation parameter β(k) representing an adaptive beam pattern configured to attenuate unwanted noise as much as possible under the constraint that sound from a target direction is essentially unaltered, and ∘ a resulting beam former for providing said resulting beamformed signal Y BF based on said first and second electric input signals IN 1 and IN 2, said first and second sets of complex frequency dependent weighting parameters W 11 (k), W 12 (k) and W 21 (k), W 22 (k), and said resulting complex, frequency dependent adaptation parameter β(k), where β(k) is determined as β k = 〈 C 2 * C 1 〉 〈 | C 2 | 2 〉 + c, where * denotes the complex conjugation and 〈·〉 denotes the statistical expectation operator, and c is a constant,