Development for Seven Month Old?

My baby boy just turned seven months old yesterday. He has been developing normally for all his milestones. The only one that is really, to me not on target is the speech. Books, emails updates and magazines are all saying your baby should be bababab, gagaga, mamama, dadada. My child is not even close and doesn't look interested. He will stare at you and ahhhhh in different tones. He will haaaaaaaa at our dog or people that he's trying to get their attention. Is this normal? He will smile at me and about any other person talking to him. He laughs, crawls, sits very well and sleeps through the night. What can I make of all this so I can stop worrying for right now? Please suggests or input.