@mike_in_nc thanks for the sound rock tip.
Most definitely, though they are rare today. I was raised in a New England house with lath, horsehair, and plaster walls, and you can tell the difference just walking into the room. The random thicknesses of the plaster (and maybe the horsehair) reduce resonances, I guess. Wallboard is just a huge drumhead.
I think it is related to wall stiffness(?).The plaster is so much stiffer than drywall.
The good part about drywall is that the skirting boards (baseboards) pull the drywall to the board as much as the board to the drywall, when one is using screws..
On plaster they both need to be straight.
I did not take measurements when I did a counselling room with thick 5/8” drywall and green glue. But it sounded also most like a plaster wall at that point in terms of sound coming through the wall. It was really the solid core door that was dominant at that point.
It is great that the @ei001h is doing this electrical stuff now…
I would probably add in some conduits for ethernet, fibre, etc… One can always suck through a string with a vacuum to pull a different cable later if there is a conduit in place in the guts of the wall.