Analysis of calculated pulse shapes for ultrasonic waves reflected from a plane transducer is made with respect to the effect of transducer thickness and transducer backing material. Conditions affecting convergence of the amplitude value of the infinite series of pulses internally reflected in the transducer are discussed in detail. The significance of the acoustic impedance of the sample under study as well as that of the transducer is shown to be an essential criteria in selection of transducer backing material.