Sonic resonance in a sandwiched electrorheological panel

We have studied the sound transmission properties of a flexible sandwiched electrorheological (ER) panel. It shows that, at a frequency range of 80-150 Hz, the sound pressure level spectrum exhibits a resonant peak. The resonant peak makes a shift to high frequency and the phase of the transmitted wave changes with an increase of the applied electric field. A vibration-radiation model is set up to simulate the sound radiating process and verifies a resonant effect in the ER panel in qualitative agreement with experiments. The tunable resonance effect in the ER panel would be useful in constructing tunable phononic crystals and other acoustic devices.