I saw a youtube video with an industrial unit that also resulted in the ringing ears phenomena. I think you're probably right about the "class of its own comment."I just got done using my new machine. At first I didn't think it was working, because the usual test wasn't working. But I spoke with the factory, and they told me this model doesn't test the same way as others. The thing with this one, the frequency is such that when it is on your skin it vibrates through your body and you hear a ringing in your ears, sort of like what you might imagine a dog hears when you blow a dog whistle. Kind of irritating, actually, but it lets you know it's actually working. Obviously, I won't know what the results are for a while. But first impression is, this machine is in a class of its own.