Sound travels further in cold weather (2019) (opens in new tab)

They do, I notice the effect in my area every year. In summer I can't hear the traffic on a highway a mile away, in winter I can hear it. Insects and birds make noise in summer also, which raises the background noise level.

All you need is a bit of hard vacuum in between, even micrometer thick layer is enough. Now how to do it continuously without joining parts is a bit of challenge now

That is because light is a particle itself whereas sound is potential energy cascading through matter

For the first not so easy - what about soundproofing ? (For sound to be able to vibrate through an object, the object itself must be able to vibrate. This is why extremely dense materials make for great soundproofing as they are too thick to vibrate. Mass is a fairly straightforward soundproofing principle — the greater an object’s mass, the harder it is for sound to shake the object or push through.. - colder air is heavier, so energy (even if more ..or regardless(?) of transmission (into..?) ) to shake it shall last for shorter distance - right ?)

About the second: When air is colder, the molecules are closer together, so sound transmission should be easier. This is true of solids and liquids, but gases behave a little differently. When gases heat up, their molecules move much more quickly. This increased vibration transmits the sound more quickly than it would in colder, but more static, air. ( https://www.soundproofcow.com/sound-travels-different-materi... )

That also sounds off because you're putting it as if yours is the only effect; don't you still have to combine what you say (less background noise, if I get it correctly - I do wonder about what SPL levels you're talking about here, and in any case they will be orders of magnitude smaller than sound produced by a train for instance, so does that noise still matter than?) and what the article says (inversion)? tldr; please elaborate, preferably with references.

That's not fixed at all, that's an opinion; the dictionary (several) says either is fine.

There is no final, undisputed arbiter of what is right and proper in English, no Academy of English, no written law. Maybe there is consensus within a social group, nation, or profession, but a whole lot of these things are not provable.

Less/fewer is another one where people pipe up and claim one is "correct" (again, according to whom?), when in actual fact, either is fine and no-one cares and it's not provable either way.

Do you have any reference for this ? The article says nothing about that. It says that sound travels further in a channel of cold air between warmer air and ground (it could be water even better).

I think it's the opposite: in lower temperature the air density is bigger and it's mass so energy to move the same mass shall exhaust (heat) at shorter distance..

Sound travels further through cold air.