idiom · the urgent beating of gongs and drums, traditionally used in Chinese opera to signal a start or a character's entrance

戏台上突然响起了紧锣密鼓，观众们立刻安静了下来。

idiom · to make intense, urgent, and frantic preparations for an upcoming event or activity

校庆活动的筹备工作正在紧锣密鼓地进行中。