Soundproofing. It's a small fraction of building cost, but one that is most often omitted because short term profit is disconnected from long-term utility and benefit.
I've experienced several absolutely miserably loud neighbors. Talk about destroying my potential.
I moved to a house -- way more space than I need -- to get away from it. To end up with neighbors who blasted their car stereos -- think SUB-woofers -- all day long. In an unincorporated community where there was no noise ordinance and the county sheriff left it up to the individuals to sort things out.
Another necessary component: All you "libertarian", laissez faire people need to decide whether you are really, fully behind that idea. In which case, I would have no problem going across the street and putting a slug in each of their heads.
If I'm going to solve a problem, then once and for all.
Otherwise, come up with some effective noise control ordinances -- AND EFFECTIVE, PRO-ACTIVE ENFORCEMENT AND PENALTIES.
So... if you want "new cities" including "denser" living, fix your fucking noise problems.
US houses and apartments seem notoriously poorly insulated when it comes to sound. As you say, its a small extra cost, and it can allow for more people in an area (even having connected townhouses or apartments) without having to deal with neighbor noises. If you can fit 3x the number of houses into a lot and they have good sound insulation, you're producing a lot more revenue from the house sales as well as generating potentially much tax revenue for that area of land (depending on how property taxing is done there)
New development in for example NYC has very strict requirements on how much noise can pass through walls, ceilings and floors. I live in a tower that was just finished in 2015, the floor-to-ceiling windows are double-pane glass (no air gap, looks very thin), rubber mounted rim all around. It's absolutely, completely, silent. I have never heard a single noise from a neighbor either. Open a window, the traffic noise from the street is intense (and messes up the climate control, so no need to do that).
So, it's definitely possible to build densely with great soundproofing, and is now often required by the building code in bigger cities. Of course old stock won't be magically converted, but will also improve with time as they get renovated.
I think the trick to that is to get rid of sprawl. You have a lot of people thinly spread out but still emitting light pollution. Move people in closer to city/town/village centers, out of meandering suburbs, you move the light pollution to centralized locations, and are able to leave more surrounding land for rural uses with little to no light pollution.
I've experienced several absolutely miserably loud neighbors. Talk about destroying my potential.
I moved to a house -- way more space than I need -- to get away from it. To end up with neighbors who blasted their car stereos -- think SUB-woofers -- all day long. In an unincorporated community where there was no noise ordinance and the county sheriff left it up to the individuals to sort things out.
Another necessary component: All you "libertarian", laissez faire people need to decide whether you are really, fully behind that idea. In which case, I would have no problem going across the street and putting a slug in each of their heads.
If I'm going to solve a problem, then once and for all.
Otherwise, come up with some effective noise control ordinances -- AND EFFECTIVE, PRO-ACTIVE ENFORCEMENT AND PENALTIES.
So... if you want "new cities" including "denser" living, fix your fucking noise problems.