Rookie Mum: baby babbling

My little boy, Tom, pulls at my leg and points excitedly at the sky, babbling frantically. "Ma dada baba duka duka duka!" he says. "Duka duka ba ba ba ba!" I look at him and ask, "What is it?"
"Ba baba duka ka ka kaaa!" he says, barely able to contain his excitement. I gaze upwards in an attempt to decipher what this is all about. Then I spot it. There's a helicopter flying overhead. He loves helicopters.
"Yes, Tom. A helicopter!" I say. I repeat it for good measure: "Good boy! Helicopter."
These exchanges are sometimes frustrating. Tom tries to tell me something, but the problem is we speak different languages - me English, him baby-babble. I feel bad when I don't know what he is saying, and he gets frustrated when I don't react the way he wants me to.
I am getting increasingly impatient for my toddler to talk.
He can say "oof oof" for dog, "car" and "bird". He can also say "Peppa", his favourite pink cartoon pig.