It builds on the technology behind laser microphones. According to the paper, visual vibrometry has historically required expensive cameras, and their method removes this need and appears to have other advantages over using a high-speed camera. They say they contribute “a novel method for sensing vibrations at high speeds (up to 63kHz), for multiple scene sources at once, using sensors rated for only 130Hz operation. Our method relies on simultaneously capturing the scene with two cameras equipped with rolling and global shutter sensors, respectively.“