It already exists in the form of silent flashing blue lights. Anyone who hasn't already seen these lights approaching will usually panic when they suddenly hear

It already exists in the form of silent flashing blue lights. Anyone who hasn't already seen these lights approaching will usually panic when they suddenly hear a loud siren and become more of an obstacle than if they just carried on moving forward as normal. I see this scenario played out every weekend when I visit a friend who lives near a busy intersection of two major routes. Emergency vehicles impede their own progress nearly every time by deploying sirens.