For human ears, hearing this tongue is dangerous. It's somewhat like having a song stuck in your head that you can't quite remember the lyrics to, although it's a bit more intense than that. This language (called the First Language or La Salessa Divinia) causes pain to human minds when it's spoken, read or heard, burning at the listener's consciousness or even driving them insane if they don't have the willpower to withstand its force.
Even as she suffers due to its influence, for Alice the First Language is the most beautiful speech she's ever heard. What do you think? Here's a sketch of a brief English to Divinia dictionary I put together during the earliest stages of writing the book.