[mdip]

This is a clever approach and it got me wondering a few things.

An hour or so from where I live there have been complaints about an infrequent low rumbling sound for years[0]. I'd wondered -- at the time -- why you couldn't just do something like they do with the gunshot detectors to find the source of the sound[1]. I suspect there must be a technical/physics reason that I am not familiar with. This article re-enforced that thinking for me -- I think I've heard one of these air cannons, before (I have not heard the Windsor Hum), and its characteristics seem more like a gunshot kind of sound than what's described here but ... if you can record the time it starts from three different points (and all you're looking for is "an area roughly the size of a large factory" because it had always been suspected to be one of the plants along the river), wouldn't this approach have been simple/cheap enough to do to figure it out[2]?

[0] https://www.npr.org/2020/08/04/898853311/it-took-a-pandemic-... -- it was solved because a steel plant shut down and the problem went away.

[1] Part of the problem was that a subset of the population could hear it and a subset of that population noticed it enough to be bothered about it so it kind of led to a large number of people dismissing complaints as "people who complain about WiFi signals harming their health"

[2] And if I answer my own question: I suspect it probably was and I suspect the reason it wasn't done is that nobody cared enough to do it, really. :)