I’ve heard some people can hear this (or at least feel it) and find it incredibly disturbing.
So are you a Yooper transplant to Dixie???
There are two settings, audible and high frequency. My wife can here the high frequency sound and says it hurts her ears. They claim the high setting is for small dogs, but I haven't needed to use it.
Yes, I grew up in a small town just north of the Wisconsin border. Now I live near Raleigh, NC.