const int sampleWindow = 50;+
unsigned int sample;

void setup()
{
   Serial.begin(9600);
}


void loop()
{
   unsigned long startMillis= millis();
   unsigned int peakToPeak = 0;

   unsigned int signalMax = 0;
   unsigned int signalMin = 1024;

   // collect data for 50 mS
   while (millis() - startMillis < sampleWindow)
   {
      sample = analogRead(0);
      if (sample < 1024)
      {
         if (sample > signalMax)
         {
            signalMax = sample;
         }
         else if (sample < signalMin)
         {
            signalMin = sample;
         }
      }
   }
   peakToPeak = signalMax - signalMin;
   double volts = ((peakToPeak * 5.0) /1024);
  double decibel = 20*log(volts/0.005012);
  Serial.print("zvuk_u_decibelima:");
   Serial.print(decibel-20);
   Serial.print(",");
  Serial.print("zvuk_u_Voltima:");
   Serial.println(volts);
}