Why Do The Firefighters Do This?

The firefighters I live across the street from have a bullhorn on the outside. My bedroom faces it. When at 2 am I am hearing this thing go off about heart attacks, babies etc. but they dont pull off. I asked them why its on at these hours and they say 'Its the only way to hear the calls' but in winter you NEVER hear it on, day or night. If It were me and a frat house I would be called in violation of a noise ordinance. so why do they get a p? Pittsburgh, station on S.18th st. (below the tracks) why are they being douches?