I agree SCtrky. The various words, chalk, chuck, church, etc. will help some but be absolutely useless to others. I like your idea of finding someone that is proficient on a call and then asking them to make the same sounds with the call out of thier mouth.............again not foolproof (cause everyone probably makes slightly different sounds) but I bet it could be helpful.................wonder why those guys in the video's haven't thought of your idea yet?