i think sometimes sentences that you may never use in real life are still used for learning the words themselves and how to use them. it might be simple to memorize useful phrases but if a really weird sentence stikes you as odd you may be more likely to remember the actual pieces of the word, and by consequence, the words and rules surdounding them. idk if that makes sense. but not all duolingo sentences need to necessarily "make sense". language is like that, you can make up a bunch of random weird stuff but the grammar rules are still applying to the language when you say things like my horse just turned purple or the thing between space and the space between my teeth. i just made those things up they dont really "make sense" but they illustrate the language english. i hope i made sense lol. also, i've noticed some other comments saying this sounds poetic, and sure, "between my ears" is logical and normal but if you Were to put that into a poem, you might "play around" with the language and get this sentence instead. i like that about language, sometimes sentences that seem to mean the same thing as a logical, straight forward sentence give off something extra just because of the way they are said.