Obviously there are some pieces of information that can be conveyed better with a picture or diagram - network connections, block graphs, etc. But as a general rule text is far more efficient for knowledge transfer.

If I have a text file and an audio file of the Great Gatsby, and I want do any of the following, then I'm going to use the text file:

* Find a particular quote

* Determine the number of times the word "Gatsby" is used

* Go back a few pages to remember exactly how something/someone was described

* Intermittently stop and compare with a supplementary file and/or write notes

* Find exactly where I was just before I fell asleep

* Get through it in 3 hours without rushing or missing bits

* Store it on a portable device along with thousands of other books

There is no such general rule, and humanity has always used various media, and for every biased test you come up with (frequency of a word in a text) you can just as well come up with a test that benefits the other medium (frequency of some sound in the audio book)

* Go back a few pages to remember exactly how something/someone was described

Or you don't forget how someone looks because a visual illustration is easier to remember

* Find exactly where I was just before I fell asleep

You can't, the book closed when you fell asleep and you forgot the bookmark . But when the phone fell it disconnected your headphones which stopped the playback.