title: Emission enhancement of sound emitters using an acoustic metamaterial cavity.
abstract: The emission enhancement of sound without electronic components has wide applications in a variety of remote systems, especially when highly miniaturized (smaller than wavelength) structures can be used. The recent advent of acoustic metamaterials has made it possible to realize this. In this study, we propose, design, and demonstrate a new class of acoustic cavity using a double-walled metamaterial structure operating at an extremely low frequency. Periodic zigzag elements which exhibit Fabry-Perot resonant behavior below the phononic band-gap are used to yield strong sound localization within the subwavelength gap, thus providing highly effective emission enhancement. We show, both theoretically and experimentally, 10 dB sound emission enhancement near 1060 Hz that corresponds to a wavelength approximately 30 times that of the periodicity. We also provide a general guideline for the independent tuning of the quality factor and effective volume of acoustic metamaterials. This approach shows the flexibility of our design in the efficient control of the enhancement rate.
authors.affiliation: Department of Nature-Inspired Nanoconvergence Systems, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 305-343, Korea.
authors.forename: Kyungjun
authors.initials: K
authors.lastname: Song
authors.affiliation: Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 305-343, Korea.
authors.forename: Seong-Hyun
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon, 305-701, Korea.
authors.forename: Kiwon
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Nature-Inspired Nanoconvergence Systems, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 305-343, Korea.
authors.forename: Shin
authors.initials: S
authors.lastname: Hur
authors.affiliation: Department of Mechanical Engineering, Pukyong National University, 365 Sinsun-Ro, Nam-Gu, Busan, 608-739, Korea.
authors.forename: Jedo
authors.initials: J
authors.lastname: Kim