unsigned long now, lastaction = 0;
const byte buzzerPin = 11;
const byte switch1Pin = 12;

void setup() {
  pinMode(switch1Pin, INPUT_PULLUP);
}

void loop() {
  now = millis();
  if (digitalRead(switch1Pin)==LOW){
      if (lastaction == 0){
      lastaction = now;
    }    
  } else {
    lastaction = 0;
    noTone(buzzerPin);
  }

  if (lastaction>0){
    if (now-lastaction>5000){
      tone(buzzerPin, 494);
    }
  }
}