I have called in several bears in Washington State. 16 so far. I like to use a loud raspy mouth call. I start off quietly and increase the volume after a few minutes. I call in a bear about every 20ish stands. I call non-stop for at least 45 minutes and try to make it 60 minutes. I have the best luck, obviously, when I have a lot of fresh sign, but do a lot of cold calling. I believe if you hear the bear coming in, most often the bear is a larger bear. I think they are trying to intimidate whatever is eating whatever is screaming. Most mid-sized and smaller bears sneak in because they don't want to rush in and get their butts kicked. I had to pepper spray a small sow several years ago. I was calling and heard some pine needles crunching behind me and slowly turned and about 15 yards behind me was this small sow. I did not want to shoot such a small bears so I softly spoke to her and she stepped forward. I stood up and said hey bear. She pinned her ears back and started towards me so I sprayed her in the face and she left. Another time I was calling with a buddy and his young son. I was calling, slowly turning my head looking and there about 10 yards in from of me was a pair of beady eyes and a pair of ear looking in my direction from about 15 feet. All I could see was the top of his head over the ferns. I kept calling and raised my gun and shot him between the eyes. Scared the crap out of the guy I was hunting with. A few times calling I never heard the bear come in, but would catch movement and watch them turn and walk away. It is very effective, but you have to stick with it. I think most guys are not successful because they give up too soon and don't try it enough times. I like to put my watch out in front of me, so I can keep track of the time, because calling for that long, feels much longer.