4 year old singing

Does anyone have a child who constantly sings? My 3 almost 4 year old is always singing. I mean constantly. Really loudly and a lot of times not actual words just sounds. He'll do it when someone is trying to talk to him, someone is reading to him, during a movie, when he's playing, while he's eating, the list goes on! If he can't sing because there's food in his mouth or something, he's humming.