Hello,
I usually dont use this type of stuff but I have no clue whats happening. I just installed a fresh copy of everything (LSDPFR, cars, sirens, scripts etc) and when I fired up my game the sirens and some other sounds (burnout sounds, can hear car but not the tire). I'm using the American Sirens Pack 1.4, i've also tried not using the mods folder that kind of stuff but i cant seem to get it working.
EDIT: Wierdly fixed itself...