Wow.. the article and the comments here are fascinating. I don't have much to add, but I think what you guys are calling overtones are something some of my fri

Wow.. the article and the comments here are fascinating. I don't have much to add, but I think what you guys are calling overtones are something some of my friends and I used to do as kids. One person would sing or yell a single loud note and another would sing or yell a sliding scale of notes listening for the overtone where a "spooky third voice" would chime in. We made up stories about it being a ghost summoning ritual and such. :)