Sounds crazy, right? Not so fast!
I am able to do this with my low cost Red Head Owl Call. Im sure anything similar would probably work. Use the tip of your tongue as a way to control the air as it is forced into the call and through the reed. Roll the tip of your tongue like your making the sound of a machine gun. You control the loudness/duration. I usually cup one of my hands around the tube end towards the birds. (Pictured is the call I use). Its pretty easy. Good luck!
I was on a solo hunt a few years back, it was closing in on noon and I was getting ready to call it. I had been working on two strutters across a field for an hour and I just couldn't get them to come towards the tree line no matter what I threw at them. So, I busted out my owl call and put my tactic to the test. Working my slate and the owl/gobble call I finally got the birds undivided attention..and wouldnt you know it? Those birds came in on a string to check things out, close enough to meet some Nitro #5s.
I suppose I discovered this new tactic by accident, but Im glad because ever since I use it regularly. Whether I'm roosting birds, provoking them, or stealing away that hen to bring him in, it works. Try it, it may just help you when all else fails.