"They will not shield the cartridge from extraneous vibration ( sound) as well if at all.".
There is more than one way of shielding from vibration. I favour unsprung TTs, no added springs elsewhere (boing boing) - who says vibrations can't pass through springs?
Mass isolation is the best vibration insulator by far. No moving parts. Just a big slab of concrete, stone or marble that would take a ton of force to move it, not a small vibration. My support is mainly marble and must have a total weight of 1200 pounds or more. It also isolates phono amp, pre-amp, power supplies, CD and SACD players.
My isolation