@@ThunderboltSiren1003 IIRC it is merely just the alternating wail of the Federal Signals Modulator. There was one in downtown chicago that had to be replaced/removed as- if my information is correct, it had a stumble.
I live in California next to Los Angeles about 1 hour away from where I live and they have sirens model 5,model 7, 2t22,flower siren, Sd-10 and think modulators and ATI also ASC makes sirens for California incase of a tsunami but I’m going to get a thunderbolt a 2t22 or a H.O.R super sirex from Arizona.