Silicon platforms are widely recognized as an industry standard for photonic integrated circuits. However, conventional tuning mechanisms, such as thermo-optic and plasma dispersion effects, impose limitations in advanced applications, such as quantum computing, where low-loss and cryogenic operation are critical. Acousto-optic (AO) modulation offers a promising alternative, broadening the scope of silicon photonics. Here, we investigate an aluminum nitride (AlN)-silicon hybrid platform to enable AO modulation on silicon waveguides. The AO interaction is enhanced through a Fabry-Perot resonant cavity, achieving a π-phase shift voltage (