I am converting one of my bedrooms into a nursery which I would like to soundproof. Currently, the wall is 1/2 inch drywall attached to studs. No insulation.
I am reading a lof of different suggestions with each one saying the other one is no good.
I want this room to be soundproof so a baby can sleep without being disturbed.

I read put insulation in the walls won't do much. Adding a second drywall will do nilch.

What can I do to soundproof a room so the rest of the house does not need to walk on eggshells when passing the baby's room?