[mlsu]

With the energy efficiency attainable by traveling in the upper atmosphere, this might be the greenest possible long range transportation.

God such a tantalizing solar punk dream. I would love just to hear the inside of an electric commercial airliner at altitude.

[VBprogrammer]

Presumably they would use something like an electrically propelled ducted fan (basically the first stage of a high bypass engine). The noise I imagine would be reasonably similar.

[nerpderp82]

I think a hybrid approach with a high bypass turbo fan powered by an electric motor. The fan could then switch over to a https://newatlas.com/automotive/inside-out-wankel/ when at cruising altitude. Using biofuels, or carbon air capture, we get long range and a closed carbon cycle.

[_puk]

I doubt it would be classical music and whale song playing over a beautifully calm scene..

More like kids watching movies without headphones, over loud conversations and screaming babies if other public transport is anything to go by.

But we can dream!

[SapporoChris]

Experiences vary. I was on a Tokyo subway train (Chūō-Sōbu Line(Local)). For a couple of minutes after boarding it was so quiet that it was eerie. When I started hearing quiet noises I relaxed.

Anyway, mass transit does not have to be noisy. It varies by custom and culture.