"Ellos oyen los colores."
It is about synesthesia. https://en.wikipedia.org/wiki/Synesthesia I expect a doctor or someone talking about psychedelic drugs to say that. With limited vocabulary most sentences here are going to be only for teaching proper verb conjunction. You can easily replace "colores" with any device that makes a sound when you learn it.
Nonsense in language is fine, once you are the master of it and a poet, but confuses beginners struggling to learn basic rules. Using provided definitions, I translated as, "They hear the colored pencils." (As if heard scratching on paper). Makes more sense than solution but was marked as incorrect.