"And there came a voice from heaven, saying, Thou art my beloved Son, in whom I am well pleased." (Mark 1: 11)
Three verses report on what God said after Jesus' baptism: Matt. 3: 17, Luke 3: 22, and this verse in Mark. Only Matthew has God saying "this is" my beloved son. Mark and Luke both have "thou art."
What does the one word difference imply?
To me, the change seems to indicate a different intended audience. In Matthew, God is speaking to the people who are present, bearing testimony, as it were, of Jesus.
In Mark and Luke, however, the words are clearly intended for Jesus himself--as a reassurance, perhaps, that his course thus far has been pleasing in his Father's sight? As a revelation that his intimations that God is his father in perhaps more than the way in which God is the father of all human beings are correct?
Or did Jesus simply need to hear the voice of God in order to start his ministry? Did he need to hear directly in that moment: "you are ready"?