User blog comment:FairyRaven/Fairy Tail Chapter 400: Wings of Hope, Review and Commentary/@comment-18654001-20140913113607/@comment-4829046-20140913114253

Rather than being detected while they were concealing themselves, it would be interesting if it was because having direct conversation with another hidden dragon could deplete the factor by which they manage to stay inside. Just a random thought. :)

Also, this could mean we finally get to see Acnologia say something. If he doesn't, then damn, I feel sorry for Igneel and co. That, or maybe he simply can't speak anymore and we only see him do it when he is about to die.