The behavior of coherent acoustic phonons (CAPs) as they propagate through a material is a function of the material’s optoelectronic and structural properties, making these collective oscillations a multi-faceted characterization tool. While CAPs are usually detected using transient reflectivity measurements, they have also previously been observed directly in real space using ultrafast electron microscopy (UEM). Here, we report use of UEM to measure localized CAP behavior in an amorphized and annealed GaAs specimen, and demonstrate...