Noise shielding using active acoustic metamaterials with electronically tunable acoustic impedance

Noise pollution has become one of the most serious problems of our society. Considerable part of unpleasant noise is transmitted into the interior of buildings through large vibrating planar structures windows with poor noise-isolation properties caused by their low flexural rigidity. In this Paper, we demonstrate and analyze a noise shielding using an active acoustic metamaterial (AAMM) with electronically tunable acoustic impedance. The AAMM consists of a curved glass plate with attached piezoelectric Macro-Fiber Composite (MFC) actuators shunted by negative capacitor (NC) circuits. Using this approach, it is possible to electronically control the effective elasticity of the MFC actuators and, therefore, the flexural rigidity of the composite structure of the AAMM. Key features that control the acoustic impedance of the AAMM have been analyzed on a simplified analytical model. Frequency dependence of the acoustic impedance and the acoustic transmission loss through the AAMM are measured and compared. Vibration modes of the AAMM are optically measured using Digital Holographic Interferometry (DHI).