When Jesus Christ lived a perfect life and died for the sins of men, He qualified to dethrone Satan. The "god of this world" has been defeated! However, he remains active among us until the King of kings returns and sets up His government on earth.
Richard T. Ritenbaugh
Basic Doctrines: Satan's Origin and Destiny
In this example, taking place shortly before Jesus' suffering and death, a gathering of Greek visitors and probably some of His disciples are present (see verses 20-22). They all hear the voice. Jesus says the thunderous voice was made audible for the sake of His visitors. At such a troubled time, it was no doubt encouraging for Him as well.
Jesus speaks to His Father in the presence of the Greek visitors, and His Father audibly answers Him. Some compare the voice to the sound of thunder. Others think an angel has spoken to Jesus. Could it have been an angel speaking? No. The voice says that the Speaker had glorified His own name, so if it were any other being than the Father, this declaration would be false. Surely, the Father would not delegate the duty of glorifying His name even to an angel, especially at such a pivotal time.
The Voice of God