A microphone unit having only one PCB, a plurality of transducers of acoustic-electric type with digital output mounted on a back side of the PCB, through holes obtained in the PCB in correspondence with each transducer, an A2B audio interface mounted on the back side of the PCB and electrically connected to the transducers; and input/output electrical connectors mounted on the back side of the PCB and electrically connected to said A2B audio interface; the plurality of transducers include a central transducer and at least three peripheral transducers disposed at the same radial distance from the central transducer and equally angularly spaced. A microphone meta-array includes a plurality of microphone units connected by one or more A2b networks.