A day or two into a visit to any non-English speaking place, hearing English being spoken becomes something really noticeable. I can be in a crowded cafe with everyone talking. But if someone within earshot is talking in English it jumps out at me. And then when I come back home there's that brief transition period, where every conversation I hear jumps out at me. It doesn't take long before I acclimate and my brain stops reacting at the background sounds of my native tongue.
The weird thing is that's already happening now in Montreal. I took a walk earlier today shortly after we arrived and kept noticing all the English speakers around me. Now I'm in a cafe a few hours later and I realize that I have started ignoring the background English. It probably has a lot to do with the neighborhood we are staying in, but it's funny to feel the adjustment start with three days left before we go home.