fezzness

Ugh, I have had this horrible problem ever since i d/l cars and the mod installer. I re installed everything and still when i play it does this faint background-ish sound to car noises, weapons but like sounds like crashing into something or cut scenes or other cars still makes noises its just any noise i try to make in-game. I dont know what else to do I d/l a sound mod to see if that would make it work but no avail. any tips yall got?