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Comment by ocdtrekkie | Hacker News Reader

Three people so far have suggested in the comments here it should be "easy" to triangulate it. Note that according to Zug Island's Wikipedia page, "As of April 2013, a Canadian scientist is using sound-level meters and a portable "pentangular array" of cameras and microphones to try to precisely identify the source of the sound, in order to know whom exactly to ask to fix it" and that "the City Council had already spent over $1 million to help Windsor and Ontario find the source of the noise".

I think there's a bit of armchairing going on here, in that people are definitely trying the obvious already.

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At that point the city should just organize a contest and give 1 million to whoever finds it. For that much money I'm convinced someone will.

They can triangulate it unless... (puts on tinfoil hat) ... the hum is coming from under the city.

It's probably something planted by the Wayne County government to try and get people to move to the US side.

No tinfoil hat needed. It is very possible for some machine at the steel factory to have foundations in a slab of deeper bedrock that becomes more shallow where the noise is more prevalent. The noise would just come from 'everywhere'

They need to deploy a shot spotter that cities use to quickly locate gunfire and dispatch police.

https://www.forbes.com/sites/alexknapp/2013/06/28/shotspotte...

I'm always disappointed to see that people think the description on that system's tin is its actual purpose. It does that, yes. What else?

That's some scary stuff right there. Who controls what it's used for? How transparent are the data? Yikes!

With laughable accuracy: http://fox61.com/2013/05/22/fox-ct-investigation-is-costly-g...

Part of the problem is multipath due to reflections caused by buildings, hills, trees, etc. Anytime you listen to thunder or fireworks the rumble persists due to reflections off of such things. It's incredibly difficult to algorithmically remove multipath from terrestrial sources.

Correct. At 30 Hz directionality is a pipe dream.

It's relatively trivial to find direction of the 30 Hz sound source, given 1 million budget - you just need to place microphones 11 meters apart and raise them above buildings until you get direct line of sight to the main source.

A million bucks wouldn't get a square city block of what you describe.

A square block? 5-10 microphones is plenty. Your goal is to find a direction from the place you deploy, not to blanket the city. Then you can redeploy somewhere else to get another direction, etc.

That's an example of how poor directonality is at 30 Hz.

> I think there's a bit of armchairing going on here, in that people are definitely trying the obvious already.

As one of these suggesters - I think it's the problem lies in that the article doesn't mention this obvious first step in determining the source.

"Since reports of it surfaced in 2011, the hum has been studied by the Canadian government, the University of Western Ontario and the University of Windsor."

Do you really think that between the Canadian government and two universities, over the past seven years, that you are the first person to suggest this "obvious first step"?

I went to school and worked for a while studying spectrum management. It boggles my mind to this day that drones get in the way of fire fighting and emergency services because an obvious first step world be to allow emergency vehicles & helicopters to jam the frequencies of drones. There are plenty of other vehicles with this ability (military, secret service, etc) so it's not like the technology to solve the problem is unobtainable or non existent.

Would that be legal? Does the FCC offer such an exemption to laws prohibiting signal interference? And in what capacity? We've seen law enforcement jam cellular networks, but firefighters and EMTs? Helicopters? Should civilian helicopters also be able to jam signals? Would all this signal jamming (mostly of Wi-Fi bands) interfere with emergency services equipment or the ability of victims to call for help?

Jamming equipment is heavy, bulky, expensive, maintenance intensive, and especially power hungry. Plus due to the vagaries of signal propagation the effects are somewhat unpredictable. Installing jammers on civilian helicopters would be totally impractical.

The problem is that there's an infinite number of possible frequencies. Most Hobby drones use one of the ISM "junk" bands (eg 900MHz, 2.4Ghz, etc), but it's impossible to jam ALL of the possible frequencies without wiping out communications over a wide area.

Well, that we should know from the article.

It mentions investigations many times:

"Since reports of it surfaced in 2011, the hum has been studied by the Canadian government, the University of Western Ontario and the University of Windsor."

Those are all the links in the article, the last one (https://www.dropbox.com/s/vi8ek3hqiof81ca/UW%20Study%20Repor...) gives us

"For the duration of the project, the Hum manifested on only a handful of days, which made the identification of the source difficult. Good data representative of the Hum was measured using the stationed noise monitors. Conclusive evidence of the source was not achieved using the NSI system since the Hum was not present on those days that this equipment was deployed on the river. The conclusion of the research is that the Windsor Hum does exist and has both qualitative and quantitative characteristics that surmise the likely source of the Hum to be from the blast furnace operations on Zug Island."

So the main problem of the article is that it tries to make a mystery from something reasonably good investigated.

From what I understand, it is mostly an issue of jurisdiction. The factory is in the US, and the problem impacts people across the river in Canada.

Cross border noise pollution was likely never envisioned in any international treaties, so there is no obvious legal means to resolve the problem.

Yes there is. At least with frequency assignment. There are very strict policies that any frequency usage within 50 miles of an international border must be approved by the appropriate authority on both sides. The rules may not apply to non-communication based sound (which is an obvious failure), but it's not like there is no framework for this kind of thing, it just doesn't extend far enough.

typical triangulation would depend on the sound being heterogeneous in waveform/volume right? If it's a constant hum then you'd only have volume dissipate as you move away which would get a lot harder as sound has different loss functions as it moves through different materials.

No, the triangulation you would use for a project like this would look for time delay or phase lag between 2 (or more) adjacent microphones.

The sound pressure wave is picked up by one, then some few microseconds later, it appears on the other(s) a few centimeters away.

This is pretty straightforward with ordinary sounds that dominate the signal. You could pick out the wire which was struck in a piano, and even the nodes and harmonics along its length.

It gets more difficult at lower frequencies and with quieter signals, which precisely describes this exact situation.

You can't do this with a sine wave. It's impossible to exclude waves caused by reflections.

What I don't understand is if they are just trying to locate sound source or looking for other waves, such as electromagnetic ones. When I walk under high voltage trellises I always hear my head humming.

You don't 'hear' EM waves. What you're hearing near high voltage lines is coronal discharges near the conductors; The field strength is high enough to ionize the air around the conductor causing it to move around, moving air = sound.

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