Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

An automatically adaptive metamaterial sound absorber is designed, which can absorb tunable low-frequency (<500 Hz) sounds under ventilated conditions by designing a feedback circuit to actively detect the noise signals and adjust the sliders on the reconfigurable absorbers. The automatically adaptive ventilated absorber provides an intelligent route to adapt for different low frequencies, through adjusting the sound absorption units directly in accordance with the external environment while retaining high-efficiency absorption and ventilation. The intelligent sound absorber is demonstrated experimentally and the effective model of coupled lossy oscillators is employed to understand its mechanism. In the future, the absorber that is fabricated can be adjusted to adapt for different working frequencies in stunning applications such as ventilated smart windows, which not only effectively solves the influence of external noise but also provides a fresh and bright working environment. The automatically adaptive absorber should also find promising applications in ducts, where the frequencies of noises can vary time by time, and it is often difficult and inaccurate to manually tune an absorber in such scenarios.