An audio system has a circular microphone array with a number of microphones arranged on a circle for receiving a sound field. A digital signal processor is provided for processing output signals from these microphones. To establish well controlled and sharp directivity patterns the audio system performs a weighted integration of the sound field on predetermined portions of the circle. The weighted integration can be performed in a pre-processor reducing the number of channels by creating a smaller number of virtual microphones or by selecting specially designed microphones