However, my blissful thoughts were suddenly and rudely interrupted by the racket going on next door.

racket 是名词，意思是"喧闹声、吵闹声"，指持续不断的、令人不快的噪音。这个词常用来形容大声的、令人烦躁的声响，比如建筑工地的噪音或邻居的吵闹声。