Heard something similar on the Mosquito Tone Test site. There are 10 levels there. I can hear 7 on speakers. 9 with headphones. My students (some of them anyway) say it drives them crazy! Sooo, I may get the ringtone for my own reasons! Am 49 btw.
This is not new. I experienced "bio-feedback" back in the seventies. The object it to calm your thoughts or brain activity to reach a blisslike state. But cool its now in a toy!!
Yeah, QUISP!!