I spent most of Sunday morning searching for and subsequently scanning hundreds of newspaper headlines going back almost 200 years. I have more than 20 years background in qualitative research, but this was a challenge. The signal to noise ratio on my searches was distressingly low. But note that anybody can do this research; you just need to scan the archives. Here’s an excellent source: http://pointstothepast.ca/.
I found a rich record of unexplained sounds. As an aside, I feel thankful to live in this era when I can learn so much in so little time. I’m old enough to remember the time when I had to approach the reference desk in the Faculty of Education at the University of Manitoba with my educational database searches, and then return a few hours later to learn the results. And then I had to repeat the entire exercise, even if I wanted to tweak a single word in my search. What I did Sunday morning would have taken months in 1984.
I may have found some very early references to unexplained, low frequency sounds that were heard mainly at night. But I must mention reports of the “huge swarm of bees” sound that even today – and I mean this actual day – are reported to the World Hum Map and Database. I’ve always agonized over this description, because I always assumed that the collective sound of bees was a mid-range frequency. But apparently I was mistaken in that. The following serious research indicates a high spectral density around 110 Hz – well within the range of what we are studying. https://igor.crew.c-base.org/1-s2.0-S0168169908001385-main.pdf, and this: http://www.beehacker.com/wp/?page_id=103, and others. There is a chance that the worldwide Hum has been around for centuries. I can’t conclude anything yet.
But there’s more. Several amateur scientists worked behind the scenes, and helped to establish the modern theory of seismology. They documented the reports of people in England who claimed that there were audio precursors to minor earthquakes, as well as concomitant sounds. Their descriptions of those sounds struck a very familiar chord with me, having read tens of thousands of reports sent to the Hum Database.
My reading continues. Please let me know what you find.