A hearing instrument includes a signal processor, and at least two microphones for reception of sound and conversion of the received sound into corresponding electrical sound signals that are input to the signal processor, wherein the signal processor is configured to process the electrical sound signals into a combined signal with a directivity pattern with at least one adaptive null direction θ, and wherein the signal processor is further configured to prevent the at least one null direction θ from entering a prohibited range of directions, wherein the prohibited range is a function of a parameter of the electrical sound signals.