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.