I never thought of it that way but it makes sense. My hearing is fine and I can pick out quiet sounds, far away sounds, high-pitched sounds, etc... But I always have trouble turning the sounds that comes out of people's mouths into words especially if there's other noise. It's not a focus issue, either. I'm probably just bad at hearing speech in those situations for some reason.
I feel research in this area would be very relevant to foreign language learning. At some point you go from hearing gibberish to individual words, and then to being fast enough to assemble the words into meaning.
