Abstract: A two phase composite acoustic backing for an ultrasonic transducer array is formed of a first composite material which is electrically conductive and relatively attenuative to acoustic energy and forms a plurality of isolated conductive paths between individual elements of the array and the back side of said backing. The isolated conductive paths are surrounded by an acoustic kerf filler material which is non-conductive and is either attenuative to acoustic energy, exhibits a low acoustic impedance, or both. The resulting two phase composite acoustic backing thus attenuates ultrasonic energy which enters the backing from the transducer elements, both in the conductive paths and in the surrounding kerf filler material, while affording points of electrical attachment to cable wires for the array which are removed from the piezoelectric material.