Measure the noise level using a microphone module and Arduino

				
					/*
  Microphone VCC connected to 5V, OUT connected to analog input A0
 */

// Connect microphone output to analog input A0
#define MIC_IN A0

// Sample window width in milliseconds, 50ms = 20Hz
int sampleWindow = 50;

void setup() {
  // Initialize serial communication at 9600 baud rate
  Serial.begin(9600);

  // Set microphone input pin mode
  pinMode(MIC_IN, INPUT);
}

void loop() {
  // Read analog sensor value to get voltage
  double soundSensed = sampleSoundPeak();

  // Convert sensor reading to voltage value
  double volts = (soundSensed * 5.0) / 1024;

  // Output voltage value
  Serial.println(volts);
}


/**
 * Detect the maximum input difference (peak-to-peak) of the microphone sensor 
 * within the specified time window.
 * Returned value range is 0 - 1024.
 **/
double sampleSoundPeak() {
  // Record start time
  double startMillis = millis();

  // Save maximum value during sampling, initially 0
  int signalMax = 0;

  // Save minimum value during sampling, initially 1024
  int signalMin = 1024;

  // Store current value read from microphone
  int sample;

  // Collect data for 50 milliseconds
  while ((millis() - startMillis) < sampleWindow) {
    // Read data from microphone and store in sample variable
    sample = analogRead(MIC_IN);

    // Discard invalid readings
    if (sample < 1024) {
      // If current sample is greater than maximum value
      if (sample > signalMax) {
        // Update maximum value
        signalMax = sample;
      }
      // If current sample is less than minimum value
      else if (sample < signalMin) {
        // Update minimum value
        signalMin = sample;
      }
    }
  }

  // After collecting data, calculate peak-to-peak value (max - min)
  int peakDifference = signalMax - signalMin;

  // Return peak-to-peak value
  return peakDifference;
}