Oh sorry, I was waiting for a new post 
So, I'm thinking you might have double or more instances playing simultaneously?
I have had stuff like that going on... So for certain sounds/situations, I will use a simple frame-counter to make sure the sound is only played at certain minimum intervals....
something like :
int counter = 0;
Update()
{
counter++;
if (counter >10)
{
counter = 0;
playSound();
}
}
-the same sound played twice right after each other will sound like one louder sound.