It is an inside remark, that only students who ask, will discover. Rather random, but when you learn to sing with your spirit, your angel inside you, or outside intelligences (spirits) can sing through you.
Sarakiel comes in with a very deep voice (when channeled), and it frightens people, though this is a very righteous spirit -- he sounds rather dark... because his/it/her role and nature is war against evil... I'd say this archangel has a heavy metal voice, after a fashion.
"No one knows what they mean," is something this angel said of the mysteries uttered by God's spirit, as in the Tower of Babel story, or the idea of parables, in which only those who have God's spirit can understand the mystery.
NOTE: I try to use he/it/she or it -- because angels are without any gender at all... they are beings of energy and consciousness, light even, and do not have meat-suits like we do. Their idea of sexuality is merger, uniting in thought and energy, intermingling minds and hearts. Yet, this said, some angels tend to favor masculine or feminine forms, when manifesting to us (that is to say, when they choose to appear as a human to us, they will take a male or female form sometimes).