Thanks - this is a great answer. With regards to your objections;

Those vague relative words - your 'often's and 'rarely's - they'll keep coming up as these questions continue. What to compare to? I try to compare to an imagined hypothetical 'typical' person, who has a broadly similar life to me. What does typical mean here? Is my idea of typical the same as the question setters'? Am I accurately imagining their hypothetical existence? Could the question setters have avoided this problem by wording the question differently? A big 'i don't know' to all. It gets me to an answer and that's all I need.

As for the second point, what the question is specifically about, for me it's significant that they used the word 'notice'. It's not 'do you often hear sounds' or even 'are you often aware of sounds', it's 'do you often notice sounds'. And I think to notice something you have to assign some meaning to it. Whether that's as a coherent thought, associating it with an object in the environment, having an emotional response, getting a physiological reaction. It needs to be in your awareness as a piece of information you can do something with. If you ask someone "do you hear that?", and they furrow their brow for a moment, then go "oh yeah!", then they could hear it the whole time, maybe were even bothered by it, but only in that moment noticed it.