Dog hearing is significantly better than human hearing, and they can hear in the ultrasonic range – very high frequency sounds inaudible to humans (remember those dog whistles that never seemed to work? Same principle).

Vacuum cleaners tend to put out loud ultrasonic sounds that are irritating and frightening to dogs. They attack the vacuum because they just want it to shut up. So if you have a dog, it might be kind to put him or her outside or in another room with the door closed while you vacuum. At the very least, you’ll spare your vacuum cleaner some teeth marks.

By Katharine M. J. Osborne

My dogs are terrified. Is it the loud noise? It’s such a loud, shriek, uniquely awful sound. You guys know what I’m talking about. That thing really drives my three dog’s nuts! Ricky and Rusty is the most hate it. How about your dog feels?  

By Me