Influence of Media Loss on Semipassive Piezoelectric Sound Absorption
The piezoelectric system shunted with negative impedance elements theoretically has a broadband sound absorption. However, sound absorption of the system is limited by many factors. The dielectric and mechanical losses of the piezoelectric system seriously deteriorate the ability at certain frequencies. According to the sound absorption and electric elements formulas, the electric elements have imaginary parts because of the loss. The imaginary part of the capacitance has important influence on the sound absorption ability. If a paralleled resistance is introduced into the shunting circuit to form the imaginary part, it is dependent on the frequency. Sound absorption would increase only in the narrow band, and at some frequencies the system with the shunting circuit would even become unstable. Therefore, the method of forming the broadband imaginary parts must be studied further.
KeywordsPiezoelectric Negative impedance Sound absorption
This research was supported by National Natural Science Foundation of China (NSFC50605062).
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