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 ju

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.