not sure about that.....youtube is always good and to be honest the easiest way is to find some videos or cds of live turkeys then just keep working on your calls until you feel they are as close to the live bird sound as you can get them.
calling is like golf, you can always get better and you will never master it so keep expectations reasonable. Also you dont have to be a pro caller to kill a bird. If you spend enough time in the woods you will hear some real hens that sound TERRIBLE.
