CAPS LOCK please tun OFF.
I know you know its on because you get a nice little popup asking you to turn it off.
What kind of overflow is it? If its a hang on oveflow you could try adding a second U tube as this sometimes helps with the sound. Nother thing to do is to lower some airline tubing down the drain line until the gurgling noises stop. What your doing is in effect giving the drain line a snorkle tube so it can breath.
Another approach would be to contruct a standpipe in the overflow.