Then how is argon better than nitrogen and oxygen?

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.

> 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?

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

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

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.

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.