So here's this. https://www.youtube.com/watch?v=YWrEaG1 ... e=youtu.be
This thing looked good, but was in bad shape. It hiccuped on windup, and started off extremely soft, then got louder. Then it decided to switch to dual tone halfway through the "test." Then, at about 42 seconds in, you may hear a sound similar to that of a helicopter. Well, that was the siren, and it shut off shortly thereafter, with no winddown.
You may be able to hear a Thunderbolt in the background.