How strange it is, that despite living with ourselves all the time, we never actually truly see our own faces. We see reflections in mirrors, and still photographs, and low-quality movies, but we will never actually see how our own face looks when first we come across a cute puppy, or when we are reunited with a loved one.
This powerful self-separation is the reason that we judge ourselves as others see us, rather than as we see us – because we don't. It is also true that just as we don't see ourselves, we don't really hear ourselves either. We hear what we are thinking of and what we intend to say, but our minds are often much to cluttered and distracted to actual hear the sounds our mouths are making.
To be honest, humans aren't very good at paying any attention to ourselves at all. It's not like this should really be surprising, though, as we can't seem to pay much attention to others either.