I Agree with you, Welsh. And Fleetwood doesn't bat an eye at digital sounds, but I know I have heard of a behavior expert somewhere, somehow using a sound DVD and leaving it on for the dog at increasing volume. Perhaps it was in a book-- Grisha Stewart maybe??
Anyway, I bought a cap gun for that purpose, and I failed at that time at introducing it under threshold. And then it broke, within about 5 minutes, because it came from the dollar store. LOL! I did find, though, that with the caps in, it was scarier because of it's random fire and inconsistency. It didn't fire every time, it was like *snap snap snap snap POW snap POW POW snap snap snap snap snap snap POW*. I think that made It even scarier. So next time, I shall introduce it without the caps.