Of course, the first thing we have to do is listen to some samples. While these play, keep in mind how easy it is to fake videos such as these today. Sounds can be taken from the Internet from any source, and it requires no more than journeyman computer skills to add a sound to a video and apply any manner of reverb or background noise to it. But regardless of their origin, these are the types of sounds that characterize the Sky Trumpets phenomenon; so if there is something to explain, this is what they sound like.
Here's one from Beijing, China:
And here's one from Indonesia:
And from Saskatchewan:
And from Oklahoma:
So far, all of these Sky Trumpet recordings were posted to the Internet after 2011. Here is what amateur researchers have determined is the earliest of these videos and certainly the most popular with over 4 million views, and it was uploaded to YouTube in August of 2011, from Kiev in Ukraine, by someone calling herself "Russian Kristina":
Since this video went live, there have been any number of copycat hoax videos posted using the exact same audio file; including one that got a bit of press, by a girl who did the whole thing in five minutes to show her friends how easy it was to make a hoax Sky Trumpets video.
But hoaxes aside, it's a virtual certainty that at least some of these videos are genuine, and represent real sounds heard by real people who recorded them and posted them online in good faith. Given that, is it then proven that Sky Trumpets are a real -- and unknown to science -- phenomenon?
A good way to think about Sky Trumpets is to compare them against two other phenomena we've talked about on Skeptoid. Think of ball lightning from episode 192. Many people have reported it, but when we look at the descriptions, we find that these numerous reports have almost nothing in common, with the alleged ball of lightning differing in every significant way, from its size, shape, color, behavior, location, duration, even sound. Clearly, many different things are causing these sightings to which witnesses are attaching the generic label "ball lightning". If such a thing exists at all, science has never even come up with a consistent description, let alone proof.
The same goes for certain mysterious sounds. When we examined "the hum" in episode 90, we found that this low rumbling sound heard by people all over the world has, in fact, been explained in many of the cases. And it's almost always been something different. Often it's been an actual sound, usually coming from some industrial equipment or diesel engine. Sometimes it's been a neurological disorder or a condition like tinnitus. Sometimes it's remained elusive. But the one thing we can say about it for sure is that it's not a single thing. It's many different things, and possibly there isn't even any such thing as a "hum" coming from anything new.
Sky Trumpets give every indication of being the same as ball lightning or the hum. It's probably many different things, most of which are perfectly mundane. Certainly it's possible that some of the trumpets are coming from a source that is so far unknown to science, but we've never yet had reason to reach that conclusion. "Unknown" means nothing more than that; it doesn't at all mean that it's coming from something we haven't seen before. Hopefully it does mean that, because that would be awesome; but no matter how much we love new discoveries, there isn't one hiding behind every strange report.
Let's take one example. Here is the sound from a Sky Trumpet video recorded in May 2015 in Terrace, British Columbia:
It sounds perfectly like the trumpet of Gabriel announcing the return of Christ (and any number of completely serious YouTube commenters said as much). But then, after a number of Terrace residents had reported the sound, a City of Terrace spokesperson, Alisa Thompson, announced that the sound had simply been "a city worker grinding down the blade on a grader" at the City of Terrace Sportsplex skate park. Surprisingly, a great big steel blade being ground can make a reverberating metallic sound. And if we recall back to the sample Sky Trumpet sounds at the beginning of this episode, it just might be that similar activities were responsible for other recordings.
But of course, people aren't grinding grader blades every day. But there's one heavy metallic sound that does happen every day, and it happens everywhere in the world where there is industrialization. Listen to this sound:
Could you place it? I probably wouldn't have. It's the brakes on a train. Train tracks blanket the planet, and every day uncounted trains have noisy brakes, and they use them somewhere in the world where there are people nearby. If you were going to make a hoax video of Sky Trumpets, train brakes might well be a great source for your audio.
Another source would be Hollywood. In addition to audio, Hollywood provides inspiration. In 2011, the movie Red State told the story of a group of Christian fundamentalists who were hoaxed into believing the Rapture was coming by a group of kids who played trumpet sounds through a giant siren horn:
And just as a reminder, here's a snip from the original 2011 Kiev video, which was uploaded to YouTube about six months after the release of Red State:
It's not the exact same audio file, but the similarity is clear. To my ear, the Kiev sound has more train than Red State in it. It's certainly possible that "Russian Kristina" in Kiev saw the movie and was inspired to make a hoax video using train or other industrial sounds. Red State had not yet been released in Ukraine when the Kiev video was made, but it had been out in the United States for a while and was currently in at least one European film festival; but either way, the bootleg movie industry is not unheard of in Ukraine. However, it's not even necessary to try and connect Kristina's video with Red State, despite their similarity; the Kiev sound was weird enough that if someone heard it, it would be perfectly reasonable for them to post it to YouTube. None of these possibilities would surprise me. Is it possible that something new is responsible? Certainly, but so far there doesn't seem to be much need to go searching for anything.
But not all of these sounds are trumpetlike and easily matched to industrial noise. Listen to this sound from Japan:
And this one, recorded in March of 2011 in Florida:
The voices on the lengthy recording indicate that they thought a tornado was on its way, and they weren't the only ones to call 911. The multiple reports prompted the National Weather Service in Tallahassee to issue the following Special Weather Statement:
THERE HAVE BEEN SEVERAL REPORTS OF VERY STRANGE SOUNDS FROM THE WOODVILLE AREA SINCE ABOUT 645 PM EST. THE NATIONAL WEATHER SERVICE BELIEVES THIS PHENOMENON IS BEING CAUSED BY THUNDER FROM DISTANT LIGHTNING STROKES… BOUNCING OFF A VERY STABLE LAYER ABOVE THE GROUND. THIS IS CALLED DUCTING… AND CAN ALLOW SOUND TO TRAVEL UNUSUALLY LONG DISTANCES. THIS SOUND HAS BEEN MISTAKENLY ATTRIBUTED TO POSSIBLE TORNADOES… BUT WE AT THE NATIONAL WEATHER SERVICE WANT TO BE VERY CLEAR THAT THERE ARE NO TORNADOES… AND NONE ARE EXPECTED.
Ducting, they say? Yes, that's a thing, but it rarely applies to noise, almost always to radio signals. Tropospheric ducting is when a signal refracts back down toward the ground from a temperature inversion layer. This is very familiar to amateur radio enthusiasts. You can actually see them sometimes; since light is also electromagnetic radiation, ducting is what causes certain superior mirages like those we often see on the horizon looking out to sea.
The reason it's so rare for atmospheric ducting to do anything unusual with sound is that sound doesn't travel very far; rarely far enough to be affected. It has to be a really, really loud sound; and thunder is one type of sound that's loud enough. If the conditions are just right, as it seems they may have been on that day in 2011 in that part of Florida, very loud noises can propagate unusually far, complete with reverberation.
And even that's not the end of a story that may be still being written. Natural explosive noises, perhaps like those in the Japan audio sample, are called brontides, and there is some evidence (albeit a small amount) that novel forces in nature may produce such sounds. A few researchers have reported ground-to-air acoustic transmission from shallow earthquakes too small to be felt, and the term has also been provisionally applied to a minority of the loud booms over the east coast of North America during 1977 and 1978 that could not be correlated to sonic boom events. Brontides have also been proposed for other well-documented mystery booms, such as the so-called "Barisal guns" of India or the "Seneca guns" of New York. It's a field of study that has more hypothesis than data, and so far geologists have found little reason to follow up; so embrace brontides with caution.
As nearly everyone carries a digital audio recorder these days, we might expect these "UFOs of the audio world" to be on the rise. But so far this hasn't happened. The reason might be that the very same interconnectedness has made strange sounds easier to identify. So before you retweet that YouTube video of a Sky Trumpet, first toss it out to a community like science bloggers. There's a chance that it might be something new to everyone, but a better chance that you'll learn something new to you.