To set the stage you are hunting dark timber with noisy clutter & downfall, nearly impossible conditions to put a silent stalk on this bull, calling is your best bet!
Outside of bulls bugling competitively because of hot cows in the mix Advertise type bugling is right there at the top for the most common bugle heard. Bulls that do this generally hold position as they bugle every 1-5 minutes, they do this to draw cows their way that may be within earshot, it's one way they will use to build a harem or just seek out cows they hope are near breeding. You'll find that no other bulls are bugling this bull at this time. -- For best odds give this bull what he's looking for, no need to shut him up or push him off by bugling him because you misread his message.
After hearing a few bugles from the bull to cement your thoughts he's advertising himself & he hasn't moved cow call back to him once within 150 yards or so after his next bugle, this shows him you heard him & are interested in him. Now it's cat & mouse, will he come to your calling or do you have to go to him! It's all about the bulls attitude or if he already has a small harem that he doesn't want to leave, instead this bulls calls you to him. When you cow call again he will most likely respond back with a short round up bugle, he's asking you to come over to him, you'll notice if you hangup there he will hold position & call to encourage your approach, you must now go to him or he will eventually shut up or leave! Get wind & cover & softly cow call your way right to him, there's a good chance you will hear him raking a tree Displaying for you as you get closer, this is deadly aggressive!
On other side of coin once you cow call from aprox 150 yards the bull should respond shortly, you may notice his sounds are getting closer, this is a bull that will come to you, setup accordingly. Make him look for you & make sure he's in your range before he can see where source of calling is coming from your setup. Call just enough with very soft calls, even casting these sounds behind you as you coax him in, stop all calling if you know he's close or you see any part of him.