A tunable acoustic metamaterial based on piezo buzzers and passive circuits

The limitation of current acoustic metamaterials with fixed properties or working at fixed frequency ranges once they are fabricated promotes the investigation of tunable metamaterials. Here, we propose a tunable acoustic metamaterial consisting of piezo buzzers and passive circuits. An analytic approach is developed to analyze the acoustic characteristics. Results show that the exterior passive circuit can induce a band gap at wavelengths much larger than the structure size. In this gap, the structure behaves as an effective medium with positive density and negative elastic modulus. Our work provides a feasible and simple approach to design adjustable acoustic filters or insulators.