Active Buzzer

If it is an active buzzer, that is, a buzzer with a drive circuit inside, the voltage used is the DC power supply. For example, the common type MSPS23A35P12 is directly driven by a 12VDC voltage.

Passive Buzzer

If it is a passive buzzer, that is, an externally driven buzzer, the voltage used is the ac pulse signal. For example, the common type MSPT14A is driven by a pulse signal to make it sound.

For passive buzzers, the symbols representing voltages are: Vp-p and Vo-p, Vp-p is the peak-to-peak voltage, and Vo-p is the peak voltage.

Vp-p (peak-to-peak) is the maximum voltage value minus the minimum voltage value (both values are vector values)

Vp-p=2Vo-p