Gregory the Dialogist

After Him a sound will roar. He will thunder with the voice of His greatness. And He will not be enquired into, when His Voice hath been heard. For the Lord doubtless turns into sorrow the life of him whom He has filled with His illumination; and the more He suggests to the enlightened mind eternal punishments, the more cruelly does He weary it with sorrow for its past wickedness; and a man grieves at what he was, because he now begins to discern the good which he was not. He hates himself, as he remembers himself to have been. …

Morals on the Book of Job, Book XXVII ↗

Thomas Aquinas

Just as the material light of heaven is below him, so also the sound of material thunder is beneath him, and so he says, "After him," that is, under him, "the sound will roar," of material thunder. Moreover, he has another spiritual voice, the teaching of wisdom, which is incomprehensible to man. He speaks about this when he says, "he will roar in the voice of his greatness," the voice which teaches his greatness, and not all hear this voice as they hear the sound of corporeal thunder. …

Commentary on Job ↗