Last year, on opening morning I set up on the edge of a small walnut plantation that abuts hardwoods where the birds roost. They were gobbling from the roost nearby and I thought it was a done deal. At fly-down I called and got a response. Then a hen came from my left and she was going nuts, putting, looking for a fight. She came up to me trying to run off the new "hen". Then she went back the way she came, yelping her head off. If I heard that without seeing it, I'd think it was a rookie hunter working too hard at calling. The gobblers went her way though.
The point is, when you are in the woods, listen to what the hens sound like. Do what they do, and even out-call them. The next weekend I set up in the spot that hen came from and did my best impression of her yelping fit. Shot a nice Tom.
Also, don't leave the woods if the first couple hours don't pan out. Toms will be looking for new hens between 10 AM and noon. I've had about half of the birds come in silent during late morning, so don't get discouraged.
I've found that there is a lot of variation in the sound of live turkeys, and that the rhythm of your calling is more important than the actual sound. Don't worry if your calls don't sound perfect.
Good luck!