Extraordinary Acoustic Transmission in a Helmholtz Resonance Cavity-Constructed Acoustic Grating**Supported by the National Basic Research Program of China under Grant Nos 2012CB921503, 2013CB632904 and 2013CB632702, the National Natural Science Foundation of China under Grant No 1134006, the Natural Science Foundation of Jiangsu Province under Grant No BK20140019, the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education,

Abstract

We investigate both experimentally and numerically a complex structure, where ‘face-to-face’ Helmholtz resonance cavities (HRCs) are introduced to construct a one-dimensional acoustic grating. In this system, pairs of HRCs can intensely couple with each other in two forms: a bonding state and an anti-bonding state, analogous to the character of hydrogen molecule with two atoms due to the interference of wave functions of sound among the acoustic local-resonating structures. The bonding state is a ‘bright’ state that interferes with the Fabry–Pèrot resonance mode, thereby causing this state to break up into two modes as the splitting of the extraordinary acoustic transmission peak. On the contrary, the anti-bonding state is a ‘dark’ state in which the resonance mode remains entirely localized within the HRCs, and has no contribution to the acoustic transmission.