How to detect piezoelectric diaphragm buzzer?

The piezo diaphragm buzzer is a piezoelectric ceramic buzzer having a piezoelectric effect by a piezoelectric ceramic sheet and a metal sheet adhered together. So how do we test the piezoelectric buzzer? The piezo bender element buzzer can be detected with a multimeter's 1V or 2.5V DC voltage file.

When is measuring first and hold two pens on the right, the black pen is connected to the surface of the piezoceramic, the red pen is connected to the surface of the metal plate (stainless steel or brass), and the index finger of the left hand and the thumb simultaneously force the buzzer, then let go .

If the measuring piezo alarm element is normal, the multimeter pointer should swing to the right and then return to zero. The greater the amplitude of the swing, the higher is the sensitivity of the electric piezo diaphragm. If the hands are not moving, the piezoelectric buzzer has poor performance.