Beginning around the 4th month your baby will start making alot more sounds. They will try and repeat what you are saying. It is around this time that you MAY hear what sounds like a word or two. They are aware of you and can see and hear alot better now.
I found that Mario picked up on alot more things I was saying than my wife. I have a deeper voice and am able to change the tone and pitch of my voice. Babies can differentiate tones. You will know when you find a phrase that the baby can identify with. For Mario one of the first things he picked up on was the phrase “Where’s the Kitty?”
Every child is different. Some progress faster than others.