First New York changed the sound of their sirens, and now the city of Ottawa is changing the sounds its snow plows and trucks make when they back up. Instead of the "beep beep beep," it's more like static. It's supposed to reduce noise pollution, and they claim you'll still hear it if you're behind the truck. They're just worried people might not associate the new sound with a truck backing up. Here's the old sound, followed by the new sound.