I'm guessing the siren speakers are mounted around a DS977. I don't know if Slovenia ever had TESLA AJSN or UEAJs installed in the past. It may be something of historical Yugoslav origin or any of the neighbouring countries of Slovenia.
There are a ton of those sirens located in Serbia. We could never figure out what they were, but they sound like an electronic E-57, which I am guessing was the idea. There is a video of one sounding, let me find it and I will post it.
These were produced by Wandel & Goltermann, likely an ESA. Sold during the cold war, they were one of the first German companies to dabble in electronic sirens, also producing equipment for emergency vehicles. Can't find too many in Germany anymore, but oddly enough there are a few ESAs in the Balkans and some K-SE arrays in France. Sounds like at least one made it to South Korea, too.
This video was shot in Bad Krozingen Ger., the only video I've found of an ESA-15. Siren is from 1981, made it just under 30 years before being struck by lightning. https://luftschutzsirene.de/viewtopic.php?f=34&t=5721