They are almost always closer than they sound. But there are a few general rules and variables that will help you make an informed decision on whether you need to move on a bird or not....

1) A bird will turn his head different directions and generally if he is on the ground strutts in circles and to and fro and this can be confusing if you are trying to pinpoint his location, so its good to hear him gobble a couple of times.... if you can get him to gobble AT you, that can be a better indicator.

2) Birds sound farther and farther away as the season gets later because the leaves and vegetation start to immerge more and more.. it has a buffling effect.... by late April a bird that sounds 300 yards off is often only half that.... THIS IS A TURKEY HUNTING GOLDEN RULE!!!!

3) Playing it safe never hurts. I too have muzzle blasted ear drums... which is the price you pay for duck hunting successfully and bringing friends along... I often second guess my ears... but being a touch conservitive has always paid off for me.