> AC units do not create a vacuum
I have to insist of this, please watch the video I linked, single-hose portable AC units absolutely create a vacuum, and single-hose designs are the only ones you can get in Europe. The air for cooling the evaporator coils comes from the room and is expelled through the hose outside. This is of course different than any sort of real AC unit.
> houses are not air tight spaces
Indeed, this is how single-hose portable AC units can work, and the more air tight your house is, the more dangerous it gets with gas heating. Installing a single-hose portable AC unit in an old building with gas heating is not only very dangerous, it is also illegal (but people do it anyway). The only way to do it properly is to install an intake valve in your apartment (nobody does this). Please educate yourself about this, it is a very serious problem.
As for AC noise in general, no, a split-unit AC system makes only a trivial amount of noise. Even a crappy window unit makes far less noise than a portable AC unit because the compressor and fan is outside for a window unit, as opposed to inside.