In k.sub.31 mode, a vibration is along an axis or orthogonal to the poling or electric field orientation. The direction of vibration is toward a face of an ultrasound transducer array. For each element of the array, electrodes are formed perpendicular to the face of the array, such as along the sides of the elements. Piezoelectric material is poled along a dimension parallel with the face of the transducer and perpendicular to the direction of acoustic energy propagation. Using elements designed for k.sub.31 resonant mode operation may provide for a better electrical impedance match, such as where small elements sizes are provided for a multi-dimensional transducer arrays. For additional impedance matching, the elements may be made from multiple layers of piezoelectric ceramic. Since the elements operate from a k.sub.31 mode, the layers are stacked along the poling direction or perpendicular to a face of the transducer array for transmitting or receiving acoustical energy.