I'm in my office right now with Monty, my girlfriend's Dalmatian puppy, and the vacuum is running. Not for a training session. I was cleaning. When the vacuum first came out you could watch the whole conversation happen in his body: ears pinned, weight back, eyes locked. That thing is loud, it moves on its own, and it showed up out of nowhere. To a dog with no file on it yet, that's a legitimate threat until proven otherwise. Here's the misunderstanding most owners have. They think the dog is afraid of the vacuum. The dog is afraid of the unknown. No track record with the machine, so the nervous system does what nervous systems do and treats unfamiliar as dangerous. That's not a defect, that's a dog being a dog. The problem is what usually happens next. Either the owner corners the dog with the thing running so they can "get over it," or they turn it into a whole event with baby talk and comforting. Both teach the dog the vacuum is a big deal. Think about the first time a fire alarm went off at work. You flinched. Then it went off for a drill, and another, and now you barely look up. Nothing about the alarm changed. Your prediction changed. It starts, it's loud, it ends, nothing bad follows. That's the entire goal with the vacuum. So here's what I actually did with Monty. I turned the vacuum on and cleaned like normal. No leash, no coaxing, no pressure. He was free to move around the room however he wanted, which matters, because a dog who can control their own distance isn't being flooded. They're gathering information. He'd drift back, watch, drift closer, watch some more, and each pass got him a little more evidence that the machine was predictable and boring. Then I sat down on the floor with the vacuum running right next to me. Now reaching me meant getting near the vacuum, and I'm the best thing in the room, so coming close got paid by my presence. He worked that out on his own. No treats shoved in his face, no "it's okay buddy." Just a calm person sitting next to a loud machine like it's the most normal thing in the world. Because it is.