Is it a stock EB ps system or another system? Is it coming from the pump or the box? Also what size tires are you running. That could have something to do with it.
My first guess would be that the pump is doing the whining and if that is the case, then it might be going belly up. That isn't a for sure without actually looking at it. If it is, you could go and do a saganaw pump conversion or rebuild the original pump. Mine whines when it is very cold out and doesn't stop until the fluid is warmed up. The other thing is make sure all the connections are nice and tight because if they aren't then the whine is the pump squirting that fluid out those leaks.
But to answer your questions, we need more info from you before we can answer correctly