Using 'blink method' and 'blink without delay method' to make tones.

[system]

void withoutDelay(int interval){  
  unsigned long currentMillis = millis();
  if(currentMillis - previousMillis > (interval / 2)) {
    previousMillis = millis();
    if(pinState == LOW) pinState = HIGH;
    else pinState = LOW;
    digitalWrite(outPin, pinState);
  }
 
}

And now?