Noise shielding system utilizing a thin piezoelectric membrane and elasticity control

The description and theoretical analysis of a noise shielding system are presented. In this system, the noise and/or sound are transmitted through the piezoelectric curved membrane, which is connected to an external feedback circuit. Using the principle of elasticity control, i.e., utilization of both direct and inverse piezoelectric effects simultaneously, the movement of the membrane as well as the sound pressure of the transmitted wave can be controlled to a large extent. Transmission loss of an audible sound through the membrane in such a system is expressed as a function of a sound frequency, geometrical properties of the membrane, and parameters of the feedback circuit. It is used for the comparison of theoretical predictions and experimental data. Using this technique, the increase of the transmission loss of about 60 dB in a narrow frequency range or about 7 dB in the broad frequency range has been achieved. The performance of this system is discussed.