I don't know where I picked it up but I will sometime if not often slightly purr into my very first yelp and carry on that way. I will also start into a sequence stop a half second and then carry on the series which is a tip I was given by one of the "Pro" hunters for one of the call making companies, has not seemed to help but just started to do it last year and the turkey were really quiet last spring, I heard far more gobbling in the Fall than I did during the Spring, I only heard one definite gobble the second to last day of the season and one that I think was a gobble but was so far away I was not sure.