This is a an economical sound detector.
High sensitivity; The module has two outputs: AO, analog output, real-time output of the microphone voltage signal / DO, when the sound intensity reaches a threshold, the output high and low signal threshold - Sensitivity potentiometer adjustment. 5 volt input.
The DO (digital output) pin is HIGH by default. When sound is detected it is pulsed to LOW. Connect it directly to an Arduino without pull-up resistors.