Have you ever wondered why your dog tends to react so aggressively toward the vacuum? Maybe you've come to the conclusion that your dog sees the vacuum as an angry monster invading your home with its tail wrapped around your hands, and your dog, as it should, is just protecting you. But sadly, this is not usually the case. The vacuum releases a high pitched sound that only our dogs can hear. The sound that they hear isn't so much as annoying to them as it is painful. So we can infer that because dogs can hear more than we can and better than we can, that noises that hurt our ears would definitely hurt theirs but at heightened levels.
The physical makeup of the dog's ear allows them to hear at greater distances than ours, as well as at higher pitches. The range of hearing for dogs ranges from 40Hz to 60 kHz, compared to our range of 20Hz up to 20kHz. This explains the dog whistle situation. To us it sounds like air coming out of a tube, but to them it could probably be described as a sound that would make your ears bleed if you listened to it long enough. When the whistle is blown dogs can't help but stop whatever they are doing and bring their attention to the source of where the sound is coming from. The whistle is a powerful tool. Trainers use it all the time, it's almost like using "free food" on people, but less of a benefit for the dogs.