Holy crap that's loud!
Youtube description: My neighbor bought a surplus Air Raid Siren and it has been living in his driveway a few doors down from me for the last year or so. He finally got the power inverter he needed to run it last night. I was in my living room when it started up. Hadn't heard that sound since they tested the sirens in my home town in the 1960's during the Cold War era. It was very surreal to hear that sound. Walked over and took the following video.