I don't like to change sounds once I have started with one. It just doesn't seem very realistic to me and I haven't had much luck doing that. Though I have talked to some others who will run a call for 15mins and if no response, then wait 5 and change sounds for another 15. Hasn't worked for me but you never know. If one sound doesn't work one day then the next timeI come back to that spot I will try another. Another tip i forgot to mention the other day, I like to use a Coyote Howler about 5 mins beforeI start calling. It sometimes gets their attention. The two that I use are the Hot Dog and Sonic Dome mouth reed, both made by Primos. Randy Anderson has a video, "The Truth3", that will teach you how to use them, I suggest getting it. Another good video is "Callin Coyotes" with Mark Zepp. His video is structured on how to hunt coyotes, where as Anderson's teaches you "a little" on how to call them. Either way they are both excellent and I reccomend getting both.

Good luck and let me know how you do.

T.R.