I have a possible little mystery...to me, anyway.
First off, I'll admit that my knowledge of the siren system used in and around Omaha, NE is extremely limited, very incomplete and potentially incorrect. Here is what I do know right off the top of my head:
-The system consists of primarily T-128s with a few 2001s mixed in.
-Boys Town used to have two 3T22s, but they have been replaced with 2001s.
-The community college near 30th & Sorensen has an Eclipse on campus
-I recall that there possibly is/used to be at least one SD-10 in the Bellevue area, possibly near Offut AFB (This is based off some comments on a YouTube video I saw many years ago)
Now, here's the odd part...I can say with 100% confidence that I heard an STL-10 sounding in Omaha this past Monday (10/7). It was about 11:05AM, and I was located near the corner of 72nd and Ames (At the IHOP). It wasn't very loud, but I could very clearly hear it sounding in attack mode. The sound seemed to be coming from somewhere towards the west or southwest, but it's tough to be certain because I was up against the west side of a building at the time, it really could have been coming from any westerly direction between north and south.
Does anyone know of any STL-10s in the Omaha metro? The closest one I personally know of is in Fort Calhoun to the north, at least 10 miles away. Although I wouldn't doubt that an STL-10 could carry that far on a sufficiently calm day, the one I heard seemed almost "too loud" and clear to have carried that far.