How can you after the fact effectively silence sound from below (floor) and above (ceiling)? Genuinely curious what's possible and not expensive.

"Expensive" is in the eye of the payer. Do you think a few thousand is expensive? A developer absolutely does. Also, it takes more space, so doing it after the fact may lower your ceiling more than you're comfortable with (assuming your landlord is even willing.)

We could solve this with code updates and strict enforcement. However, pro business types will complain that it increases rents (probably true in the short term) and drives down development (probably not actually true.) Also, better sound management generates more livable spaces that better support city growth in 10 or 20 years, which is also important from a sustainability point of view. But nobody wants to pay for that. That's "someone else's" problem.

Note: Ceiling heights are part of spec. Even losing 1" could put you out of spec.

As a renter you have very little power to do anything.

Where I live you're allowed to stick things on the ceiling as long as you take them off again when you leave.

Cheaper and easier to do it during development vs. after the fact. He wants to move to a new place with sound insulation and not do it himself.

Because installing soundproofing that effectively blocks footsteps of a 3-year old is impossible after the building was built in the wrong way.

Sound propagates through floors, heating installations, windows, cable ducts etc. If those weren't properly installed and shielded it's pretty much impossible to dampen sound without rebuilding several floors.

Assuming the poster is American, he's likely talking about a rental unit (apartment), not an owner-occupied unit (condominium).

If that's the case, what can one do to alleviate noise problems in an apartment? Changing the flooring, or adding drywall, isn't usually feasible.

We recently converted an apartment space in a mixed use building to an office. It was very loft-like with 18ft exposed steal ceilings and mostly glass and concrete walls. It sounded like a gymnasium when I lived in it as an apartment. You could hear the neighbor walking around his living room and could barely understand someone speaking normally across the room. An acoustics expert recommended a number of changes but for a rental space acoustic panels like Armstrong Soundsoak and area rugs on the wood floors (with high quality padding below) are two things we did that are removable and not as expensive as you might think. They made up about half of the dampening effect while a drop ceiling did the rest. It now sounds like a library and we can no longer hear the neighbor at all (nor can he hear us).

I hadn't thought of the Armstrong panels. How do they install? I always assumed they were permanent (or nearly so), glued to the walls.

Ours are held on with strapping and few sheetrock screws since they are way overhead but they are very light weight. Picture hangers[1] would work for a small lowdown install or maybe some sort of double stick something... you would have to repaint and patch some holes/paint but its a huge difference. While we where waiting for them to be installed we just had them leaning against the walls like paintings waiting to be hanged. Even that was amazingly different.

http://www.caseyswood.com/shoppingcart/zen-cart/images/Sawto...

Offically! you do this with a thing called "Impaling Clips"

http://www.armstrong.com/pdbupimages/209751.pdf

https://acousticalsolutions.com/product/impaling-clip/

My new favorite product name