an onomatopoeic adverb describing loud, clumsy, or frantic banging/movement — e.g., the sounds of a scuffle or chaotic activity.
夜中に隣の部屋からどたんばたんと物音がして目が覚めた。
I woke up to banging noises from the next room in the middle of the night.
子どもがどたんばたん走り回るので、床が少し揺れた。
The children ran around clattering about, and the floor shook a little.