The research is clear that multitasking is not possible. Instead, switchtasking is what we are doing when we are trying to do two things that require focused cognition. We are switching our attention back and forth so fast we rarely are ever conscious of the transition. However, it is easy to show that switchtasking is slower than focusing attention on each thing individually.
However, it is possible to do focus on one mental thing when it is combined with tasks that are routinized to the degree that they rarely require significant mental attention. For example, it is possible to safely (most of the time) walk, bike, and drive while listening to someone talk. Some of us can fold laundry, or cut grass, or wash dishes while we listen to something on our phone.
However, it is difficult to read a book, article or magazine while driving, biking, walking, folding laundry, cutting grass, or washing dishes. I have been walking while reading for the past few years and almost always go by at least one person expressing concern for my safety.
Since you can listen to any book, speaker, article, email, etc. while doing any of the things above, you can significantly increase the amount of material you are able to feed your brain. And once you get comfortable with this, you may find that you are able to increase the speed of the things to which you are listening.
My point is that is that podcasts are currently almost all free and accessible to anyone with a listening device and periodic access to the internet (to download episodes). Although the research shows that reading is faster than listening, by listening during routine tasks, we can increase our knowledge exposure by many multiples! And if you able to speed up and still learn from your podcasts, you can learn even more! I can confident I am learning at 10 times the rate that I previously read. I now listen to podcasts while doing almost anything that has become a habit that does not require much brainpower.
If you want to grow in wisdom, which we should be doing based on the teaching of almost every religion and educational institution, you should really consider to start listening to podcasts, books, articles, etc.