[nativeit]

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.

[cwillu]

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.

[stephen_g]

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...

[cwillu]

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.