Police in White County, Tennessee, spent approximately $13,000 to fit their patrol cars with the necessary hardware for a digital siren. That's right, as high-tech as that sounds, the digital siren has a clear goal: to send notifications to people's mobile phones.

  

If you're annoyed by your phone buzzing all day long and would rather keep notifications off, you might want to enable them this time. An app called Digital Siren receives information from these patrol cars and sends you a notification when emergency vehicles are nearby.