Is mass the only way? The building I worked in had problems due to us transmitting a lot of noise up concrete columns, and it was solved by isolating the source from the columns. Rubber feet were used to separate the noisey equipment from the floor.

So couldn’t you isolate the noise with false ceilings and walls that are constructed to minimise transmissions?

Both is best, but typically a 6" deep wall with offset 2x4 studs, insulation in the wall, resilient channel, 5/8" drywall (which is also fire resistant usually, with fiberglass in the core) and the right caulk and electrical install will stop all but very loud low rumbles.

The key is the installation and design of the system, though. Miss one vent, electrical cutout, or gap (or even using the wrong length of screws) makes all that material useless.