Directional sound propagation in acoustic artificial structures

Wave manipulation involves harnessing and tailoring wave properties to meet specific requirements, driving advancements across a wide range of scientific, industrial, and technological fields. A critical aspect of wave manipulation is directivity control, which has broad applications in areas such as underwater communication, non-invasive medical diagnosis, and targeted audio delivery. This review introduces various methods for achieving directional sound propagation, including both conventional techniques and emerging approaches based on acoustic artificial structures. It highlights how these methods, particularly those utilizing engineered artificial materials, control acoustic wave behavior to enable directional sound emission and transmission, with illustrative examples demonstrating their principles and practical applications. Finally, the review addresses the challenges of achieving broadband, low-frequency, and adaptive control of acoustic waves, while outlining potential future research directions in directional sound manipulation.