A method of reducing unwanted noise components detected by a sensor array comprising: deriving signals from two groups of sensors (2, 4) within the sensor array, wherein the first group comprises pressure sensors and the second group comprises sensors configured to output pressure gradient measurements; beam forming the first group of sensors to produce a first set of directional response beams (14, 16), each directional response beam in the first set having a respective steer direction; beam forming the second group of sensors to produce a second set of directional response beams (18, 20), each directional response beam in the second set having the same steer direction as a respective directional response beam in the first set (14, 16); wherein each one of the directional response beams (14, 16, 18, 20) has respective front and back lobes that extend on opposite sides of the array, wherein the front and back lobes of the directional response beams in the first set (14, 16) have the same phase as one another and the front and back lobes of the directional response beams in the second set (18, 20) have an opposite phase to one another; combining pairs of directional response beams having the same steer direction, one beam from each set per steer direction, such that the front lobes of the directional response beams in the first set of directional response beams and the front lobes of the directional response beams in the second set of directional response beams add together, whilst the back lobes of the directional response beams in the first set of directional response beams and the back lobes of the directional response beams in the second set of directional response beams cancel with one another, thereby to form cardioid beams with nulls pointing in at least one steer direction. deriving signals from two groups of sensors (2, 4) within the sensor array, wherein the first group comprises pressure sensors and the second group comprises sensors configured to output pressure gradient measurements; beam forming the first group of sensors to produce a first set of directional response beams (14, 16), each directional response beam in the first set having a respective steer direction; beam forming the second group of sensors to produce a second set of directional response beams (18, 20), each directional response beam in the second set having the same steer direction as a respective directional response beam in the first set (14, 16); wherein each one of the directional response beams (14, 16, 18, 20) has respective front and back lobes that extend on opposite sides of the array, wherein the front and back lobes of the directional response beams in the first set (14, 16) have the same phase as one another and the front and back lobes of the directional response beams in the second set (18, 20) have an opposite phase to one another; combining pairs of directional response beams having the same steer direction, one beam from each set per steer direction, such that the front lobes of the directional response beams in the first set of directional response beams and the front lobes of the directional response beams in the second set of directional response beams add together, whilst the back lobes of the directional response beams in the first set of directional response beams and the back lobes of the directional response beams in the second set of directional response beams cancel with one another, thereby to form cardioid beams with nulls pointing in at least one steer direction.