I am sorry to hear about your hearing loss. I hope you are wearing hearing protection to protect the 60% you have left!
You said you have the call on "full volume", this could be keping them away. I read where a coyote can pinpoint a mouse's location down to a few feet from 100s of yards away. The have some excellent hearing. They can sense something isn't right when the close the distance and the rabbit is still screaming like a jet engine! Try to start out on low volume and work your way up. Run a minute long burst and sit in silence for 2 or 3 mins or so. Allow the coyote to be hunting the source when it arrives. This is when a motion decoy is worth its weight in gold!
Repeat this and increase the volume a little each time. Then, when done with the stand, wait several minutes in silence just incase the louder calls are bringing in a distant coyote! Keep reviewing your hunts and learning from them. Try to figure out what can be improved and it wil happen!