Back before Citizens Band radios became a thing, back before cell phones, back before pagers, even--when the volunteer fire department was needed in the Fungal Vale, they would blow the siren. It sounded,and looked, almost exactly like that one.
The modern alert system consists of rotating speakers on poles, with very powerful amplifiers, and there are a lot more of them. There is one that's not even a quarter-mile from the bunker. (Google Earth says 0.21 miles, as the crow flies.) You can hear it inside the house, with the windows shut, so there's no doubt it's more effective.
I'm not sure when they stopped using it for that purpose. In those times, when there was a tornado warning, they'd sound the "attack" siren (which was that sound, but intermittent, with a rise and fall) and then use the "alert" (steady siren) to sound the "all clear".
I'm trying to remember: there had been a siren mounted on the water tower by the fire and police station, almost exactly a quarter-mile from the water tower in the park. It doesn't make sense to have two of these so close together, and because the water tower by the station came down sometime in the early 1980s I could easily be conflating them. And I have a distinct memory of thinking, "Oh, so they moved it here."
Oh well. So, it was a Federal Signal model 3T22 siren. I wonder what happened to it?