Manually tunable ventilated metamaterial absorbers

For most acoustic metamaterials, once they have been fabricated, their operating frequencies and functions cannot be adjusted, which is an intrinsic barrier for the development of realistic applications. The study to overcome this limit has become a significant issue in metamaterial engineering. Although with advance metamaterials past two decades, series methods such as electric or magnetic control proposed, them can only work condition no fluid passage. Some large transmission losses but sounds are essentially reflected rather than absorbed. Here, difficulty, we propose ventilated sound absorber that manually tuned range after being manufactured. During tuning achieved through intricately designed slider, high-performance absorption ventilation both ensured. tunable demonstrated experimentally effective model coupled lossy oscillators employed understand its mechanism. potential application values various complicated pipe systems require frequency adjustment it also establishes foundation future active metamaterials.