I hear sirens from the ambulance on MLK constantly. No doubt there is an emergency. However, I've noticed, and then intentionally observed, the ambulances abruptly cut off their sirens mere blocks from my location, southbound as it approaches Central with lights still flashing. At least twice, an ambulance turned their siren back on after passing 5th ave south. This happens regularly at night. Why is this? Why so loud by this location, but no sirens elsewhere? The same happens on 8th st. It seems the downtown core is spared the noise of the sirens at night.