A cut a way of typical contact transducer is shown above. It was previously learn that the piezoelectric element is cut to 1/2 the desired wavelength. To get as much energy out of the transducer as possible and impedance matching is placed between the active element and the face of the transducer. Optimal impedance matching is achieved by sizing the matching layer so that it's thickness is 1/4 of the desired wave length. This keeps waves that were reflected with in the matching layer in phase when they exit the layer (as illustrated in the image to the right) for contact transducer, the matching layer is made from a material that has an acoustical impedance between the active element and steel. Immersion transducers have a matching layer with an acoustical impedance between the active element and water.Contact transducer also incorporate a wear plate to protect the matching layer and active element from scratching.
The backing material supporting the crystal has a great influence on the damping characteristics of a transducer. Using a backing material with an impedance similar to that of the active element will produce the most effective damping such a transducer will have a wider bandwidth resulting in higher sensitivity. As the mismatch in impedance between the active element and the backing material increases material penetration increases but transducer sensitivity is reduced.