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Comment by Synaesthesia | Hacker News Reader

Wow they went as far as multiple layers of glass with argon pumped between them!

This is a common consumer product, "gas fill" multi-pane windows. Argon is used in this application because it's not very thermally conductive (it's also used to fill dry suits for the same reason). I found a pretty good "sciencey layman" explanation of "why Argon" for dry suits here, which matches the reasoning for windows: https://www.decompression.org/maiken/Why_Argon.htm .

I'm not sure how much this carries through to sound transmission and I couldn't find a lot of good literature about it. I'd have loved to see if they did any quantitive testing. It makes sense that Argon would reduce sound transmission some, but I would expect that the properties of the glass sheet itself and the interface between the panes and the frame would be more of an issue than the void between the panes.

The insulation part has a nice handwaving explanation [1]:

Heat is transmitted because gas molecules bounce back and forth in a box, picking up energy on the hot side and leaving it on the cold side. The kinetic energy in any gas molecule is proportional to the temperature, and is

E = 1/2 m * v^2

solved for v:

v = sqrt[ (2 * E) / m ]

Faster gas means faster transmission, so the rate is proportional to 1 / sqrt(m).

I don't have a good intuitive explanation for the sound attenuation. The acoustic impedance for an ideal gas is going to depend on the mass of the molecules, and having very different acoustic impedance for the two gasses at an interface will minimize transmission. So I would expect Argon to reflect more sound, but I don't have as cute an explanation as the one for thermal transmission.

[1] Also completely made up, would love to know if I'm wrong.

Wouldn't a vacuum between be better?

Yes, but then you have the danger of implosion and shards of glass flying everywhere.

That's a different kinda spectator sport.

Then how is argon better than nitrogen and oxygen?

More expensive and sexier.

What gas you fill that space with is far less relevant to noise cancelling than how the pane is mounted to the others and the floor; but "argon filled!" is great marketing bullshit.

Argon is more dense and inert.

But wouldn't density make things worse? Helium can be used for noise attenuation like this because it's light, so you get worse acoustic impedance matching between the panels and the gas. Argon is denser than air.

Helium would leak out fairly rapidly, no?

I can see the benefit of impedance mismatching but i truly think that for an application like this it cannot be worth the effort until you add in the "marketing" intangibles.

Why not fill the panels with water? gloinggg

edit: IIRC argon filled double pane windows are a thing partly because the argon doesn't absorb moisture like air does; so there's less chance of condensation happening in between the panes. So perhaps they just bought double pane panel that were commercially available and ran with the sales brochure from that to fill out a press release.

It's inert, it's abundant and it's the gas of choice in windows so it's probably simply the cheapest choice.

Argon transmits sound much worse than air. I believe it's due to the fact that denser gases require more energy to compress and decompress, thus dampening sound vibrations.

Even more fancy windows use Krypton, since it has superior thermal and acoustic properties over Argon, but is about 60 times more expensive.

Xenon would also be a candidate, but it's about 10 times more expensive even than krypton, and also has the extreme downside of being an anesthetic when inhaled.

Edit: Sorry, I guess it has better thermal properties but worse acoustic ones. Helium or Hydrogen would be the ideal gasses for sound reduction.

In general, denser materials are better (and faster) at transmitting physical waves sound and worse (and slower) at transmitting electric waves like heat.

> Xenon [...] an anesthetic when inhaled.

That reminds me of a bit of dialogue from the classic game Deus Ex (2000), where a biotech office-worker is complaining about their job:

> This chemoreceptor patent-proposal is kicking my ass. Hundley won't let me down until it's done. Hardly worth filing for, in my opinion. Who wants to smell the difference between xenon and radon?

I'm also wonder what it is about argon gas that helps prevent sound transmission.

Argon gas does not conduct heat as well as air, so it's an excellent insulator. <--- why it's used for double glazing in housing, to insulate heat transfer.

Which is interesting because the density of argon is greater than air, it does not block or insulate against sound other than the general deadening effect you'd get from multiple layers (energy loss in kinetic transfer from gas to glass to gas to glass to gas again).

Vacuum, He or H would've been better imo

This [1] explains Sound Transmission Class (STC) ratings.

> An STC label delineates how partitions and walls effectively block sound and reduce noise. Ratings are determined by broadcasting a specific auditory tone near the material, and measuring dB on both sides. The higher the STC value, the better its insulation.

From the table STC=25 means "Normal speech easily understood" and STC=50 means "Shouting not heard"

This [2] table has one datapoint comparison of "airspace" vs argon filled windows. Both have an STC of 35. So maybe it doesn't help.

[1] https://www.dillmeierglass.com/news/stc-ratings-of-glass

[2] https://www.general-glass.com/wp-content/uploads/2020/09/Aco...

I wonder if somebody vaguely remembered the effects of helium fill, which actually does reduce sound transmission, and vaguely remembered that argon-filled windows are a commercial product, and conflated the two because they're both noble gases.

Nothing about the story of this project suggests they are top-tier sound engineers, and when you don't really know what you're doing (said very respectfully) the proposition "we need to fill windows and this is what other people normally do when they fill windows" is a very positive data point.

They didn't even start with museum-grade glass for optimal filming, which to a absolute layman like me seems like they just hadn't bumped most of these problems before.

When they started doing these tournaments over a decade ago, esports LAN tournaments was barely an industry, and crowds were small. Also, MOBAs are unlike many other esport genres [1], in that the two teams have partial information about the state of the game, and illegally getting information a few seconds early can change the entire outcome of the game [2].

Meaning there was no one in the world who really knew how to build such booths. Moreover, they discovered required features of the booths over the years. In such a scenario, the early mistakes are very understandable.

[1] Think Street Fighter, or FIFA

[2] I don't think games like Starcraft has such low time tolerances on information flow. Even cheers in Dota can be enough of a clue.

Starcraft has the same problem and also uses "soundproof" booths, fwiw. I believe the practice started under SC:BW

Oh for sure, please don't read my comment in a demeaning tone - very much the opposite.

I'd speculate that with it's "full outer shell" of electrons the nucleus is more shielded and the repulsion of other Ar atoms is higher and so perhaps density is a little lower than might be expected?

Argon is commonly used for double glazed windows so I would assume that the manufacturer has the experience to do that. Vacuum insulated panels exist but since that is for insulating properties I don't know if there would be any advantage for sound deadening.

Sounds cannot pass through a vacuum, as sound is fundamentally pressure waves that propagate through air. Someone also mentioned the thermal properties of the fill gas (argon being less conductive than air) and it’s also correlated, as temperature is simply a measure of the kinetic energy of molecules, so a higher mass molecule will require more energy to move, which applies to both thermal conductivity and sound transmission.

The more you reduce these problems down to their physical fundamentals, the more related they seem to become. It’s that elegance that got me hooked on electronics engineering—our experience of the universe is remarkable in how frequently a given phenomena can be described using little more than basic principles applied recursively.

You can support two panes with a gas in between with a strip of soft rubber, whereas with vacuum, I suspect the rigidity of the frame needed to support the panes against atmospheric pressure can easily kill the gains you make in isolation.

There are vacuum insulated units [1], they need tiny plastic 'microspacers' in them to keep the glass layers apart.

1. https://www.pilkington.com/en/global/products/product-catego...

And those spacers are rigid, which will remove a lot of the acoustic gains you'd otherwise get from using a vacuum.

It's worth noting that, although the page you linked says “good acoustic performance”, the vacuum windows they offer aren't mentioned on their noise control product page, nor listed in their sound simulator tool.

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