Did God actually speak to the people? And who saw the 'Dove'?

[Patiently waiting for Truth]

I was answering C.C. about 'When did God actually speak to the people"  And of course we need to go to scripture for answers, but what i found raised a couple of questions.

I'll quote scriptures first. 

Matthew 3 v 16 & 17.

After being baptized, Jesus immediately came up from the water; and look! the heavens were opened up, and he saw God’s spirit descending like a dove and coming upon him. ¹⁷  Look! Also, a voice from the heavens said: “This is my Son, the beloved, whom I have approved.”

Luke 3 v 21 & 22

 Now when all the people were baptized, Jesus too was baptized. As he was praying, the heaven was opened up, ²²  and the holy spirit in bodily form like a dove came down upon him, and a voice came out of heaven: “You are my Son, the beloved; I have approved you.”

John 1 v 32 -34

John also bore witness, saying: “I viewed the spirit coming down as a dove out of heaven, and it remained upon him. ³³  Even I did not know him, but the very One who sent me to baptize in water said to me: ‘Whoever it is upon whom you see the spirit coming down and remaining this is the one who baptizes in holy spirit.’ ³⁴  And I have seen it, and I have given witness that this one is the Son of God.”

Mark 1 v 9- 11

 In the course of those days, Jesus came from Nazʹa·reth of Galʹi·lee and was baptized in the Jordan by John. ¹⁰  And immediately on coming up out of the water, he saw the heavens being parted and, like a dove, the spirit coming down upon him. ¹¹  And a voice came out of the heavens: “You are my Son, the beloved; I have approved you.”

What I'm wondering is, who saw the Holy Spirit in the form of the dove 'coming down upon' Jesus ?

And, Who heard the voice of God from heaven speaking ?

The Matthew scripture shoes it as God speaking to the people, but Mark and Luke show it as God speaking to Jesus. 

The scripture in John (Apostle John) , tells us that John ( the Baptiser ) saw the spirit 'coming down' and 'remaining' on Jesus.

Whereas Mathew and Mark say that he saw, that is Jesus saw, the spirit 'coming down' and remaining upon him.

My point being here that Jesus came to be baptised when many others were being baptised. For instance, if 500 people were present and all 500 saw the dove descend and heard God's voice, then all 500 would have known (and believed) that Jesus is the son of God. But, if only John the Baptiser and Jesus saw the dove and heard God's voice then only the two of them would have known (and 'believed') it. 

Also am I right in thinking that Jesus wanted his 'work' kept secret at first ? Didn't Jesus tell some that he cured to 'tell no one'