The kethuk is a single kettle-gong of definite pitch (the kethuk of the Kyai Telaga Rukmi ensemble is a pitch 2; see pages about the Javanese scales and cipher notation for more information.) It is played in one of two ways depending upon the irama (speed) of the piece. In a fast irama the musician strikes the button or knob of the instrument without letting the stick rebound or the note ring. The sound of the kethuk is a dry "Thuk" (the name of the instrument mirrors its sound). In a slower irama the kethuk is played in a kind of "dribbling" pattern somewhat like "Thuk thuk thuk thuk thuk".
The kempyang consists of two kettle-gongs of higher pitch than that of the kethuk. Either one or both kempyang kettles may be stuck and allowed to ring with a "Pyang" sound. The two kettles are pitched about a note apart, so it can be a very disonant sound when they are struck together.