CRACK' (4 letters) The term 'Loud, Sharp Sound' can be summarized by two crossword solutions: 'CLAP' and 'CRACK'. Clapping is a form of nonverbal communication that is used to express joy, appreciation, or agreement. It is often used in applause or celebration. A CRACK is a loud, sharp sound that is usually caused by something breaking or splitting. It can also refer to a sudden, sharp noise that is made when something is struck.