We worry about hoax: Some of the most prominent examples on the internet (especially YouTube) could easily have been dubbed. First and foremost, we'll keep that in mind. There are also many man-made effects and natural phenomena. But we trust our own viewership, and our viewers are reporting aberrant acoustical effects in a way that makes us want to at least take another look at (or another listen to) it. Most recently, the news reports (in mainstream secular media) have come from Costa Rica, where two weeks ago (the week of January 10, 2012) people across the nation reported a sound alternately described as a hum or a rumble, drawing the attention of seismologists, who offered no ready explanation.