A random thought

A short while ago I started up the vacuum in the kitchen. I knew before I even started it that it's sound would be met with high pitched screams and squeals from the kids. Why is that? Why do the kids scream every time I turn it on? No, that is not a rhetorical question....I seriously have no idea why they do this. I mean, these are not toddlers we are talking about. In fact, I am pretty sure the toddler learned it from the 7 and 14 yr. old. It's not as if I have tortured them with a vacuum cleaner in the past. I really don't get it. It drives me completely insane. That's all.