Abstract:The tunable acoustic lining structure can effectively control the noise at different frequency. A kind of conical lining structure is presented in this paper, the mathematical model of the conical cavity is established through the plane wave theory, and the transmission loss computing method of the conical cavity is derived. The piezoelectric vibrator is used as the back plate of the acoustic lining cavity, and it is deformed by applying the DC voltage to change the volume of the acoustic lining cavity, thereby achieving the purpose of expanding the sensitive frequency range. The LMS Virtual Lab acoustic finite element software is used to simulate the acoustic liners model combined with the volume change of the piezoelectric vibrator. For the piezoelectric oscillator with a diameter of 30 mm and a height of 1 mm of conical sound lining, the volume change is 24.1%, the frequency offset reaches 123 Hz, and the frequency change percentage is 13.9% when the voltage is raised from 0 to 500 V. While for the same size of the cylindrical sound lining, the volume change is 16.95%, the frequency offset is 69 Hz, and the percentage change is about 9.3% in the condition of the same voltage changes. The results show that the frequency offset range of the conical cavity is larger than that of the cylindrical cavity, and can realize the frequency conversion control of the noise.