During the Baptism of Jesus, it is entirely possible that the religious experience that Jesus had was an interior experience. The dove then is a symbol. The dove's hovering over the water helps us recall God's spirit hovering over the waters in the creation account in Genesis. The synoptic evangelists (Matthew, Mark, and Luke)are then saying that God's creativity continues in and through Jesus.
Did others near Jesus hear the voice that came from heaven? Do we definitively know? Please remember that heaven is a symbol for the transcendence and presence of God. Also recall our Ignatian understanding that God is in all things and all situations. Heaven is as present "on earth" as it is "in the sky." The voice from heaven is then a voice Jesus hears in his concrete historical situation of accepting baptism.
What we do know is that Jesus hears the voice "You are my beloved son; with you I am well pleased." He may have told his disciples about this experience later.
Pray with Luke 3:21-22. Imagine Jesus' hearing the voice of the Father/Mother. What does he feel in his heart?
Now imagine yourself hearing God tell you "You are my beloved son/daughter. With you I am well pleased." Do you believe it?
Ask for the grace that you need.