We developed an efficient acoustic monitoring system that uses the speckle method with a Fresnel lens for light collection and applied it to long-range line-of-sight acoustic surveillance (up to 100 m). The proposed system can effectively capture and reconstruct speech from a human target 100 m away. The reconstructed speech demonstrates a high degree of real-time performance, with a measurement error of less than 0.15%, making it suitable for a variety of applications.