I saw this clearly last night when we went to a special seminar by a Bible school teacher here in Paris. I was following along quite well for most of the time. He spoke very clearly and slowly, and I could understand him well. Because I could fairly easily understand him (although it still took some work!) I was able to remember some of the points that he made and relate them to earlier points (just the normal way you would listen to a message). At one point he began to use a word that I didn't know though, and I started scrambling in my mind trying desperately to figure out what in the world he was talking about! And because of that one word (which was quite important to the point) I have no idea what he said for the next 5 minutes. And even if I heard it and understood a lot of the words, it took way too much work to remember.
I guess everybody misses bits and pieces of life here and there. I just hope I don't miss anything too important!