Arduino Classroom Noise-o-Meter

classroom-noisemeter.ino

/****************************************
Classroom Noise-o-Meter
Modified code from the Example Sound Level Sketch for the 
Adafruit Microphone Amplifier
****************************************/

const int sampleWindow = 50; // Sample window width in mS (50 mS = 20Hz)
unsigned int sample;
int greenLED = 13; // choose your LEDs. helpful to descriptively label them
int yellowLED = 12;
int redLED = 11;

void setup() 
{
  pinMode(greenLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  Serial.begin(9600); // Serial monitor is helpful to see the readings, but not vital
}
void loop() 
{
   unsigned long startMillis= millis();  // Start of sample window
   unsigned int peakToPeak = 0;   // peak-to-peak level
   unsigned int signalMax = 0;
   unsigned int signalMin = 1024;
   // collect data for 50 mS
   // this is helpful to ensure accurate readings. 
   while (millis() - startMillis < sampleWindow)
    {
      sample = analogRead(0);
      if (sample < 1024)  // toss out spurious readings
      {
         if (sample > signalMax)
         {
            signalMax = sample;  // save just the max levels
         }
         else if (sample < signalMin)
         {
            signalMin = sample;  // save just the min levels
         }
      }
  }
  
   peakToPeak = signalMax - signalMin;  // max - min = peak-peak amplitude
   double volts = (peakToPeak * 5.0) / 1024;  // uncomment if you want to convert to volts
   Serial.println(volts);
   //delay(100);
   
/* this is the logic for activating the LEDs based on the readings
 * you'll want to tweak the levels based on the average volume levels
 * in your space. 
 * the delay causes the LED to pause when lit. experiment with altering the delay time!
 */
 
   if (volts < 0.5) {
     digitalWrite(yellowLED, LOW);
     digitalWrite(redLED,LOW);
     digitalWrite(greenLED, HIGH);
   }
   else if (volts > 0.5 && volts < 1.0) {
    digitalWrite(redLED, LOW);
    digitalWrite(greenLED, HIGH);
    digitalWrite(yellowLED, HIGH);
    
   }
    else if (volts > 1.0 && volts < 2.0) {
    digitalWrite(redLED, HIGH);
    digitalWrite(greenLED, HIGH);
    digitalWrite(yellowLED, HIGH);
    
   }
}