Commented Video Game Sound Code

int pin=13; //set pin to pin 13

void setup() {
  pinMode(pin,OUTPUT); //set pin to output
  Serial.begin(9600); //set rate of communication
}

void loop() {
  for(int duration=15;duration>=1;duration=duration-1){ //loop 15 times
    for(int freq=1700;freq<=2300;freq=freq+20){ //loop of increasing frequency
      tone(pin,freq,duration); //sets each variable for tone
      Serial.print(freq); //prints to text
      Serial.print(" ");
      Serial.println(duration);
    }
  }
}