Revelation reached human beings through messengers, angels and scripture. The intermediary’s role is to convey or signify the message; this does not require the eternal attribute of divine speech to inhabit the intermediary as a body inhabits a place.
Some theological explanations additionally distinguish special divine hearing from ordinary acoustic perception. Even there, the Creator’s attribute and the perception granted to a servant remain different things.
When a student hears a verse from a teacher, the teacher’s sound is created; its valid signification of God’s speech is a separate relation. The temporal medium does not prove the referent temporal.