Training Come to an air horn.

I was talking to a dog walker the other day, and she has done some research on dealing with coyotes. Apparently, they flatten and scatter at the sound of an air horn. This woman has trained the dogs she walks to come to her at the sound of the horn, the coyotes scatter and everyone is safe. :) The coyotes are visible, bold and going hungry this year - there has been more snow than usual. Beyond avoiding the dog parks where they have been sighted, we need a plan.

I went out an bought an air horn yesterday but I haven't introduced it to Maya yet. I'm thinking of having Maya on the long line and practicing this way:
Sound the horn
Praise the head turn (I'm sure she'll at least turn to the sound)
Say 'Come'
Treat the recall if it happens
Pulse the lead and treat the recall.

Any pitfalls you can see? Should I start with something softer? I don't expect that Maya will panic to the sound, she doesn't tend to be sound sensitive. Any ideas for faster learning?