Acoustic metamaterial comprising an array of resonators being attached to the side wall of a rigid duct is investigated in this study. We propose a resonator design by employing a pre-stretched dielectric elastomer (DE) membrane to tune the acoustic property of each resonator. Both numerical and experimental techniques are developed to characterize the acoustic behavior of the proposed device in terms of transmission loss (TL). By connecting multiple resonators, we show that a broadband TL can be achieved which combines the multiple attenuation bands provided by each resonator unit. The resulted attenuation band can be tuned by varying the applied voltage to the DE membranes, showing promising potentials such as adaptive sound control devices for ventilation systems and other engineering applications

Most membrane-type acoustic absorbers for low-frequency sound attenuation are applicable only at a fixed resonant frequency for a narrow bandwidth. Tuning of the acoustic absorption spectrum is desired to match the varying noises. This letter presents a micro-perforated dielectric elastomer actuator (MPDEA) to make a broader-band acoustic absorber electrically tunable. Voltage activation of the MPDEA reduces the membrane tension and hole size and thus enables the active shifting of the acoustic absorption spectrum. Such a membrane tuning method does not require discrete mechanical parts as for the cavity tuning method. Also presented are the analytical models to predict the voltage-induced hole size change and acoustic characteristics of MPDEA.