Interesting question, and I believe it's been answered by another series, the inheritance cycle. Where in, those who speak the ancient language cannot lie, but the main character creates a allegory poem that he can speak and not just read, because HE believes it to be true. I feel music, something pervading not just your mind but emotions would do similar. Though, the nuances that imply bear some consideration. Even in the above example I feel like they could say they were singing not making a statement.
Another addendum, is they could simply change their mind later, they only have to believe it/get into it in the moment. Afterwards they could decide NOT to walk all over you for instance.
