Unlike recent "sky sounds," this one is probably real
an interesting article recently about a phenomenon that I had not heard of before: strange sounds in the sky over Yellowstone Lake. Unlike the other recent "sky sounds" that have been fairly conclusively proven to be hoaxes, these sounds have been reported hundreds of times, over at least the last hundred years. The reports come from both inexperienced park visitors and well-established naturalists, guides, rangers, and other respected figures.
The sounds happen most often on a quiet morning, when the lake is still. An observer standing on the shores of the lake may hear a sound that seems to be approaching from a distance, like the whistling wings of a flock of ducks. The sound has a distinct element of horizontal motion, as if it is passing overhead or moving across the lake.
One of the earliest reports describes the sound as being "like a rapidly whirling current of air moving at a great speed horizontally above the lake," and that it was "a swishing sound of varying volume with a faint trace of a whistle; something akin to the sound of ducks in flight."
As someone who lives only a few hundred feet from a large body of water (north Puget Sound) I can attest that sound travels strangely over water. At night when the wind is still, I can plainly hear sounds coming from boats up to half a mile away. The sounds of engines, voices, and equipment travel much farther across water than we usually expect.
Perhaps adding to this effect is the possibility of a temperature inversion in the air above the lake. One naturalist believes that this inversion - which would be most plausible on quiet mornings, coinciding with most sightings - would serve as a sound reflector, bouncing sounds out across the lake even further than usual.
If this is the case, it could simply be the remains of distant noises carrying across the lake. The sounds of the park's geysers, distant trains, actual flocks of ducks, and more. This would certainly account for the varying nature of the sound, which seems to never be the same noise twice.
It's a pity that it is so difficult to reliably document or attempt to reproduce aural phenomena like this. But I like the idea that there are still mysteries out there in the wilderness, perhaps waiting to be solved, perhaps not!