Your first sentence is your opinion, I take it?
Your question about the McCann's route can be answered only by research. Do you intend to do any or do you expect others to do it for you?
Likewise with Rachael.
Yes, it’s my opinion based on decades of observation. If you disagree that sound within a building travels more easily than sound from inside a building to the outside of a building then I suggest you walk down a street of terraced houses and listen out for the sound of people walking around, radios, talking, playing music, children crying etc. If their windows are flung open you just might hear some of the loudest of these sounds, if they are shut I think you will hear very little, however inside the houses you would be more likely to hear sounds going on upstairs or downstairs or next door. If this doesn’t make any sense to you please say why.
No, I don’t intend to do any research, I’ll leave that to the proper researchers such as yourself. I’m only posing questions that you may not already have considered.