Actually my experience growing up in the USSR was completely different- you couldn't hear your neighbors because the walls were so thick (and not just our apartment, but all apartments that I remember), that was one of the surprising things about moving the US- hearing your neighbors through the walls.
You have probably been lucky to live in either Stalinkas or buildings built before the revolution. Buildings built before the revolution were mostly constructed for nobility therefore of a very good quality. Building build during the Stalin era(stalinkas) were also of the superior quality(and still are highly valued at Russia's housing market). Stalin's idea was that working class is a new nobility and therefore should live as the nobility. However construction rates were so slow, that by the time Kruschev came to power people were still living in wooden barracks sharing them between multiple families. Kruschevkas were never intended to be permanent housing, but rather temporary solution for the housing problem. It was intended to replace them with better quality housing once all Soviets had roof over their head. Which unfortunately never happened
"They were called khrushchevkas — five-story buildings made of prefabricated concrete panels. "They were horribly built; you could hear your neighbor," says Edward Shenderovich, an entrepreneur and Russian poet. The apartments had small toilets, very low ceilings and very small kitchens." <- from the article.
I grew up in a 5 story prefabricated concrete Krushevka in Moscow. This is my experience:
[ ] you could hear your neighbor
[ ] very small toilets
[ ] very small kitchens
[X] small toilets
[X] low ceilings
[X] small kitchens
Kitchens and bathrooms were small, but not much smaller from what I encounter in some NYC apartments. I feel use of the word "very" was inaccurate in the article.
Krushevkas may have been derided as ugly pox upon the cities, but at rubles to bubliks they got people out of communal apartments. Many families were able to live in their own spaces for the first time.
Same here. Lived in both an older 40s and 50s 5 stories building. Small narrow hallways and windows. Build mostly from ridiculous over-sized and thick bricks. But very sturdy. Don't remember hearing neighbors unless they raised an extreme ruckus (usually getting drunk and yelling at each other or kids stumping screaming while playing).
Then lived a newer (built in the early 90s concrete block 9 story building). Much nicer, big windows, larger rooms. Wall not as thick but still very sturdy and don't remember hearing my neighbours same as above. Windows were letting cold air through in the winter and elevator kept breaking often but sound proofing was find and no cracks or structural issues that I remember.
Genuine khrushevkas were made exclusively out of prefab concrete slabs. Each wall was one slab, the ceiling was one or two slabs per room and the sound isolation issue was less due to the thickness of the slabs and more due to poor fitting of the slabs or bad sealing of the joints.
I still live in an apartment of the type referred to in the story. These are indeed quite sound-proof and I found the remark surprising in the article. I would say the main sound leakage in the default design are the electric socket holes in the wall, although not much. Still, these holes were filled with foam when I moved in and now everything is rather sound-proof.