The module KY-012 Active buzzer module is part of the series "37 In 1 Sensor Module Board Set Kit For Arduino" the module consists only of an active buzzer that has an oscillator inside it so just power the buzzer and it will emit a sound, typically at the 2500Hz frequency. Through this module it is not possible to determine the frequency of the sound, for this function it is necessary the passive Buzzer present on the module KY-006 Small passive buzzer module. [For further information](https://www.adrirobot.it/sensori/37_in_1/KY-012-Active-buzzer-module.htm)