Denver siren test was today, and I was there with a friend so we talked through the test which I'm sure you'll all love! [/sarcasm] (There's still plaenty of footage of the siren alone, and the windup and wind-down are both untainted)
Anyway, this is the siren at Merrill Middle School, and sounds beautiful. I went in thinking this siren was set to CL7, but boy was I wrong!
http://www.youtube.com/watch?v=WaD7w2usDk8