This work focuses on the characterization of CuZnAl shape-memory alloy in its 3 states (austenitic, mixed, and martensitic) by a non-destructive technique to determine its elastic properties. This technique is based on the principle of acoustic microultrasound. It allows measuring the propagation velocities of the longitudinal, transverse, and Rayleigh acoustic waves, from which the elastic constants of the material (Young’s modulus $E$, shear modulus $G$) are calculated. Thus, the obtained results of the measurements allow the modelling of the acoustic signature $V(z)$ and the reflection coefficient $R(\theta)$ to compare the resulting Rayleigh velocities, which were modelled and measured experimentally in the different phases.