Professional translators often do "shadowing", which is listening to source material from the language you're weaker at and attempting to just transcribe it in

Professional translators often do "shadowing", which is listening to source material from the language you're weaker at and attempting to just transcribe it in real time. You can start with source material which is easy, such as dialog on TV shows, and move to source material which is hard, such as news broadcasts. (Newscasters speak much much quicker than characters in fiction and employ large and often unpredictable vocabularies, whereas most popular culture is dominated by the ~200 words at the head of the zipf distribution for that language.) It's totally free and, when you're at intermediate proficiency, both stupendously effective and the most maddening exercise you'll ever do. (What happens when you're thrown off the deep end into a newscast about nuclear power plant issues and you're deeply out of your depth with regards to the required vocabulary? You try your best, jot down the five words every 3 sentences you actually catch, and then break out a dictionary later to figure out why houshasen and shiyouzuminenryoupuuru seem to be so key to the topic.) ("Radiation" and "pool (for storage of) used (nuclear) fuel", respectively. And there, now you understand 5% more of that conversation.)