Get some of Ed Sceery's (sp?) videos, I think he explains them well. We are trying to play on their instincts as best we can to get them to respond in an anticipated way with a sound that best elicits that behavior. One thing that we have to take into consideration is that the "alarm howl or bark" that coyotes make when they are threatened, is VERY similar to alot of the howls we use, so if you are "off" by even the slightest amount (mostly hand calls) or respond with an electronic sound that "alarms" them, you just announced to all within hearing distance that something is just not right. I know I didn't explain it very well, but listen to Ed Sceery, he has it down.