In the office where I work, there's a meeting room which, like many meeting rooms, is separated from the main office area by thin walls which aren't part of the building's original structure.
The management decided that some meetings were very private and didn't want anybody eavesdropping through the thin walls, so they paid quite a bit of money having the walls and door soundproofed.
Except that, soundproofing or not, there remains a gap of several inches between the end of one of the meeting room walls, and an external wall which contains a window that was there before the meeting room was built.
So if you are in the office anywhere near the window you can still hear every single word being said in the room!