Many coyotes go into a instant panic when you give them two things to think about at the same time. I have used decoys quite a bit and they work much better if the sound is coming out within 12" or less of the decoy. If the sound is coming out a foot or more away from the decoy then you are giving the coyote more than one thing to think about.
Many coyotes that I have called in will stop and look at the decoy as soon as they see it, even with the sound and decoy in the same spot.
