Sound-Activated LED with Arduino

// Flash an LED when the KY-038 detects sound above its threshold.
// Turn the module's potentiometer to set sensitivity (the module's own
// LED lights when it triggers).

const int soundPin = 2;   // KY-038 DO (digital out)
const int ledPin   = 13;  // LED (and onboard LED)

void setup() {
  pinMode(soundPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // DO reads HIGH when sound exceeds the threshold on most KY-038 modules.
  // If your LED behaves backwards, swap HIGH and LOW below.
  if (digitalRead(soundPin) == HIGH) {
    digitalWrite(ledPin, HIGH);
    delay(200);            // keep the LED on briefly so the flash is visible
  } else {
    digitalWrite(ledPin, LOW);
  }
}