Noviro
嘟嘟哝哝
Simplified 嘟嘟哝哝
Traditional 嘟嘟噥噥
Pinyin dū dū nóng nóng
Definition to mumble in whispers; to mutter to oneself
嘟嘟哝哝抱怨
Tā zài dū dū nóng nóng bàoyuàn
He is mumbling complaints to himself