Riordon could only hear down to 19khz. I could clearly hear 17.4khz, and could hear 18 well enough that though I might not notice it for the brief time it would sound for a ringtone would certainly be generally annoyed, even if I wasn't sure why, by a shop keeper using it constantly. I kept clicking it to see where Rio and I differed, and I got a headache, felt a bit off, and got kinda irritated/wanted to get away from it feeling. :/ I think it's plausible even some of the higher ones I can't hear in the slightest would produce the same affect.

Rothko didn't seem to care, he was in the room the entire time we were playing with it.