The phase responses of a first and a second microphone are adjusted with first and second filters that filter their microphone signals. The first filter corresponds to a first contribution to a phase shift between the microphones and includes a first adaptation parameter. The second filter corresponds to a second contribution to the phase shift and has a second adaptation parameter. A global filter, which is formed with the first and second filters, represents the first and second contributions to the phase shift and includes the first and second adaptation parameters. The global filter determines a first value for the first adaptation parameter and a second value for the second adaptation parameter via a multidimensional optimization. The phase responses are adjusted by applying the first filter and the second filter to at least one of the microphone signals with the adaptation parameters set to the first and second values, respectively.