thump

There was a loud thump when the heavy box of books fell off the shelf onto the floor.

(Chinese) 当那一重箱书从书架上掉到地板上时，发出了一声沉重的砰然声。

I heard a dull thump against the window and realized a bird had accidentally flown into the glass.

(Chinese) 我听到窗户上传来沉闷的撞击声，意识到一只鸟不小心撞到了玻璃上。