Suggestion is more whether you want the new audio for sirens or not... the siren interface itself is really just an enhancement on its own
Basically the idea is to have 5 new sounds; wail, yelp, priority, bullhorn and hilo. Bullhorn would be able to intersect with other sounds, so instead of setting the sirens to a complete stop, it simply pauses them, and when you turn off the bullhorn, the siren continues from the frame that it was paused at. Hence the yellow font showing there's a track that's currently paused, waiting for bullhorn to stop.
Adding to this, it would be cool if any sound could intersect any other sound, so your wail doesn't start over from frame 0 after switching back from another siren.
Audio pack is from lcpdfr. Arguably the highest quality one we were able to find of that genre. Quite possible we can have different packs added for Fire/EMS if this suggestion passes.