>>both groups completed it in roughly the same (median) amount of time.

Sometimes if there is no other option people just adapt. Even if it is uncomfortable.

Besides, it also depends on the tasks you are doing. I can pretty much code any regular problem-solution pattern in a noisy set up. But if I need to debug/trouble shoot. Or if I'm doing something new which I haven't done before I need some silence and undisturbed time to focus and get it done.