In this chapter, the most important features of the dual-delay line measuring system often used in practice are described. This system compensates for the influence of some undesirable external factors on the measurement results, e.g. small changes in temperature or pressure. The system enables precise examination (by measuring frequency changes) of different sensor layers and structures made in the SAWSurface Acoustic Waves (SAW) system, placed in different gas atmospheres. In order to confirm the acoustoelectricAcoustoelectric (AE) interactions that result from changes in the electrical conductivity of the sensor layerElectrical surface conductivity of the sensor layer (σ) or structure, the planar electrical method was additionally introduced. For sensor structures produced in the same technological processes, it is possible to correlate acoustic and electrical responses, and thus confirm the occurrence of the acoustoelectricAcoustoelectric (AE) interactions.