Effect of asymmetric piezoelectric multimorph ceramic on frequency response characteristics of piezoelectric acoustic actuator

This paper proposes an asymmetric piezoelectric multimorph ceramic to improve sound quality of the piezoelectric acoustic actuator which means flat and smooth frequency response characteristics on a wide playing frequency range. In order to investigate the effect of asymmetric piezoelectric multimorph ceramic on the frequency response characteristics of the piezoelectric acoustic actuator, we compared and analyzed the vibrational frequency response and output acoustic characteristics of the piezoelectric acoustic actuators fabricated with 2 types of 3-3 symmetric and 2-4 asymmetric piezoelectric multimorph ceramics. The significant dip of 5 kHz in the output sound pressure of 2-4 asymmetric piezoelectric ceramic speaker was not only greatly by 20 dB, but the percentage of THD at 5 kHz was dramatically reduced from 96 % to 39 %, compared to the results of 3-3 symmetric piezoelectric ceramic speaker. As a result, it is obvious that the asymmetric piezoelectric multimorph ceramic can improve the sound quality of the piezoelectric acoustic actuator to have flat and smooth frequency response characteristics, compared to the symmetric piezoelectric multimorph ceramic.