Every time I've had a hearing test (which, admittedly, has been quite some time now), I've come out with a perfect score. (I always ask the tester afterward.) But I don't think that my hearing is actually perfect at all; I think that the test must just be very limited. I think that I'm pretty awful at understanding people in crowded areas, like restaurants and cafeterias. I find myself asking "what?" far more than anyone else around me. Now, it's possible that other people have the same problem but aren't actually paying attention so they don't care enough to ask for a repeat. If I'm talking with you, I'm paying attention to you. I know that's not true for everyone.
I'm not sure exactly what my problem is. I do have significant troubles picking peoples' voices out from other voices. But I don't seem to have any problems hearing faint instruments, rhythms, or other musical constructs from a complex piece. And, my overall hearing is just fine; it's not like I need people to raise their voices when they're around me.
It's got to be more of a software (comprehension) problem, not a hardware (ear) problem.