Wow, this sounds a lot like what I do. Often, I'll become so focused on something that I won't notice things that are quite obvious to everyone else. Also, someone might tell me to do something and I'll end up forgetting because I'm so focused and can't stop what I'm doing. Yet on the other hand, when I'm not hyper-focused I tend to notice more things than others do, or at least different things. For example, at a family gathering I tend to be silent and instead notice other details that everyone else seems oblivious to; flies buzzing about, when someone has left the room and no one else knows where they've gone, that sort of thing.
I've explained to a relative once or twice that I feel like my focus is a cone sometimes and everything else ceases to exist. My ears are sensitive, but my guardian is always noticing sounds in the distance that I don't because I can't be bothered to when I'm focusing on something else.