ear ringing with ultrasonics

[Shannon]

It's common for people to think that because they can't consciously hear the ultrasonics, that they need them really loud. That's why I have specific info about calibration. Also, ultrasonics don't cause ear ringing in the vast majority of people. As Subeternal said, it's very, very unusual. It seems unlikely even if you had them cranked up way too loud, unless you were blasting your head off with them using headphones and ultrasonics at the same time... which is one reason I say... don't use headphones and ultrasonics together!