Because in heaven we are not yet in our resurrected bodies, but spirits, I believe the communication would be the same as the angels do - thoughts transmitted without words. Humans on earth need words and language so that our sense of ‘hearing’ receives our thought. On occasion God Himself may speak to us in our own language through an interior locution, if necessary, especially when we fail to hear Him otherwise. Most of the time, He communicates with us us spiritually without words.
Joysong is on the right track here. Remember that language is an aspect of our temporal, earthly existence. Prior to the bodily resurrection, we shall be pure spirit without those faculties that are of a material nature, such as sight, smell, taste and hearing. Language as we know it will not exist. Recall that God, and Heaven, exist outside of time. The whole concept of “thought” as we know it does not exist there. In Heaven, our spirit is united to the Divine and perfect Will of God. Language exists, in part, to express concepts to aid in understanding. Since, in Heaven, there is only perfect worship of the Trinity, we will “understand” just as the angels do - instantly and all at once.
As St. Augustine said in
De Trinitate, it is really quite impossible to speak of God and things in eternity in temporal terms because anything finite, no matter how greatly conceived, will always fall short of anything infinite. He wrote, “now since we ought to think about the Lord our God always, and can never think about him him as he deserves; since at all times we should be praising him and blessing him, and yet
no words of ours are capable of expressing him, I begin by asking him to help me understand and explain what I have in mind and to pardon any blunders I might make… We firmly believe and maintain that whatever we say about that unchanging and invisible nature, that supreme and all-sufficient life, cannot be measured by the standard of things visible, changeable, mortal and deficient.” (
De Trinitate, Book V, Paragraphs 1-2, emphasis mine)