Cats are afraid of the dumbest things. I can understand the vacuum and the coffee grinder, but we have a couple inside cats and they are afraid of the dumbest things. We had a cat and he was afraid of a black wrist sweat band, he would claw our eyes out to get away from it. We would put it on things we didn't want him to mess with. Sometimes if I needed to laugh, I'd toss it at him to see him jump 3 foot straight into the air.