You need to hear a word 160 times in order to learn it according to recent research at Cambridge University. See these summaries in English and Italian.
I do not know if this is true. I do know that I often understand things and remember things better if I have hear them, and if I hear them more than once. I also find some texts easier to follow when I listen than when I read. Proust is a good example.I recommend repetitive listening in language learning, and I think it should also be used for other kinds of learning. What I read makes less of an impression on me than what I hear. If this can be proven it may have major implications for teaching. Maybe we need fewer text books, and less explanation, and lots of repetitive listening.I do believe the effect is enhanced when we listen to meaningful content, rather than just a meaningless list of words. At least that has been my experience.I also think that combining repetitive listening with reading is even more powerful than just listening. But that is not scientific, just my experience.