I once read that seeing your own baby smile and hearing it laugh released "happy" chemicals in the brain of the child's parents. I can well believe it. To be honest, before your baby is old enough to smile it all seems a bit of a slog, and for what? Constant screaming and feeding? But when you first see your baby smile, it literally does something to your brain (I'd like to say, "and you forget all the sleepless nights", but that's not true).
My second child has never been a particular jolly baby, it takes a lot to make him smile and I've only heard him laugh a handful of times, he's a tough audience. So here, for you, is the golden sound of his laugh. Be patient.