Ultra-broadband absorption by acoustic metamaterials

We design and experimentally realize an ultra-broad band metamaterial-based acoustic absorption material. Unlike traditional acoustic absorbers, the designed device features a simple configuration unrestricted by the material type and does not require extra sound-absorbing materials, suggesting the potential to have simultaneously structural-stiffness and environmental-friendliness. Analytical analyses are provided to explain such distinct characteristics, which are revealed to stem from the localization and dissipation of waves with different frequencies at particular spatial positions. This is also demonstrated both numerically and experimentally. Our results may offer possible designs for various applications such as noise reduction and making underwater anechoic materials. (C) 2014 AIP Publishing LLC.