Abstract: Piezoelectric micromachined ultrasonic transducer (pMUT) arrays and systems comprising pMUT arrays are described. In an embodiment, coupling strength within a population of transducer elements provides degenerate mode shapes that split for wide bandwidth total response while less coupling strength between adjacent element populations provides adequately low crosstalk between the element populations. In an embodiment, differing membrane sizes within a population of transducer elements provides differing frequency response for wide bandwidth total response while layout of the differing membrane sizes between adjacent element populations provides adequately low crosstalk between the element populations. In an embodiment, close packing of membranes within a population of transducer elements provides improved efficiency for the wide bandwidth embodiments.