Earlier quoted context omitted.
I haven't seen these, and you gave me a new fear for what people might do in public. More seriously, they seem to have better audio so they're meant for home audiophile headphone usage?
Sony MDR 605LP is an example of a very open design. I used to own a pair, and I quite enjoys listening to them (by myself). Seems like today Open-Back Headphones is more popular, they are still open in the back. The sound of the open air headphones are a bit hard to describe with other words than 'open' :-P It's just a bit more like listening to speakers.
> ... listening to speakers
This is exactly how we hear anything not live. A truly amazing time to be alive.