int Speaker = 1; 

void setup(){
  pinMode(Speaker, OUTPUT);
}

void loop() {
  for (int i=0; i < 25; i++) {
    digitalWrite(Speaker, HIGH);
    delayMicroseconds(750);
    digitalWrite(Speaker, LOW);
    delayMicroseconds(750);
  }
    delay(50);
    for (int i=0; i < 25; i++) {
    digitalWrite(Speaker, HIGH);
    delayMicroseconds(500);
    digitalWrite(Speaker, LOW);
    delayMicroseconds(500);
  }
    delay(2000);
}