On the suppressor/silencer noise bit.
Any decent can will lower sound pressure to below ~125 dbs; considered 'safe' without using hearing protection.
(let's ignore the extremes like a .50 BMG & stick to 'regular' stuff)
There is a significant difference in the sound of a sub-sonic vs. a super-sonic round being fired from the same firearm&can.
The super-sonic 'crack' is a sharp & noticable sound compared to the 'chuff' of the gases expanding.
RL I could fire a suppressed, sub-sonic .22lr in my house and someone a couple rooms away would be unlikely to notice.
Close a couple doors and the same would be true for a suppressed, sub-sonic 45ACP or 9mm.
The super-sonic crack for a small slow round (.22lr) is -very- different compared to something like 7.62x51
A suppressed 7.62's noise is quite different/odd compared to a non-suppressed shot.
The super sonic 'crack' is still quite loud and sharp, but it's point of origin is very fuzzy.
If you were a 100 yds away out in a field and someone fired a non-suppressed 7.62 you could easily point to within a couple degrees of where it was fired. Not so if it were suppressed; best you could do would be ~50-60 degree arc.
So yes, suppressed large bore pistols aren't as 'silent' as protrayed in the movies. But you certainly could fire a sub-sonic one inside an apartment without the apartment next door calling 911. Even with thin walls it would sound to the neighbor like you'd dropped something.
Basically, swinging a pickaxe at a piece of metal would be quite a bit louder. & yes, all the above from rw experiance. err.. except the shooting indoors bit, that's generally illegal so I most certainly didn't do that