I heard a priest say, "You know, of course, that angels cannot speak or sing, as they have no voice box."
If that's true, who sings in the choirs of angels? Who told Mary about Jesus' conception? Who told the shepherds about his birth? How did the angel talk to the children at Fátima?
Here’s a reply from TCA columnist Father Ray Ryland, Ph.D., J.D:
It's true that angels have no voice box, because they have no physical bodies. But that doesn't prevent their communicating with human beings.
Angels who serve God on earth have the capacity for assuming human form in carrying out their divine missions. We see many instances of this in the Old Testament.
Hebrews 13:2 refers to those occasions when it teaches, "Do not neglect hospitality, for through it some have unknowingly entertained angels."
In ways keeping with their own nature, angels indeed can speak and sing. Sacred Scripture repeatedly refers to angelic choirs around the heavenly throne. All the prefaces in our liturgy invoke the example of the angels glorifying and praising God. The Epiphany preface thus joins us with the angels' worship: "Now, with angels and archangels, and the whole company of heaven, we sing the unending hymn of your praise."
They in their way, we in ours. But there are hints in divine revelation that in heaven we shall have with the angels a common medium of communication.