For practical experiments, it should be noted that pulse-echo measurements can be complicated by the short time delay between the very high voltage pulse and the very low voltage signal measured on the same transducer. The pulse generator used in this setup can filter and amplify this signal, but this process does induce some distortion in the wave that needs to be corrected. An example of this correction process is included in the Discussion section. The rest of this section will sketch out the basic relations that enable an experimenter to calculate physical properties of a sample from the measured properties of an ultrasonic wave. More detail of the physics and mathematical details of these derivations can be found in .