Barbara...that post is the second time I've seen anything that appears to be scientific that trys to explain eartones, on this page. (the other was a NASA link about meteorites that were audible at the same time they were seen...meaning that the signal traveled at the speed of light, not the speed of sound). The article that you linked was written in a style that "sounded" scientific...there were not "red flags". The author is Larry Park, Terra Research. I can't read his graph (too small, did not appear bigger when I clicked on it), and don't know if he, or others, have really detected a real signal. I would tend to trust something more that was published in a known scientific journal...although a lot of publications have a lot of stuff that is just plain wrong...but at least you get a better look at the data. I'll do a google search on Larry Park in a minute..
Chris