6 month old doesnt babble

My son is 6 months old and doesnt babble a whole lot. He does ocassionally screech and go "ehhhhhhhhhh" and let out the ocassional babble but hes pretty quiet. His physical development is ahead. He smiles a lot and giggles but isnt very chatty at all. Should i be concerned? He does respond to his name but its inconsistent. His hearing is fine.