Haha yes, 4 months is when they discover their voice and hands can do things, so exciting but also so loud right! A few of my mum friends said their babies at this stage were like little parrots, trying out different sounds and getting super animated, which is actually a really good sign of development. Just enjoy this phase lah, it goes so fast, before you know it they'll be saying actual words and you'll miss the cute babbling days!