||The small timing bells (si:) and block (toun:) determine the speed, rate of movement or tempo of the music. There are two kinds of timing bells: those held in the hand and struck to each other, and the mellifluous bells. There are three kinds of timing blocks (wa: ). The "bjau", the wooden block (toun:) and the bamboo clapper. The time keeper in the classical song ensemble holds the two timing bells in the right hand and strikes the timing block with the left. Sometimes one bell is placed on the coin of cord and is struck with a wooden stick. The mellifluous bells and timing block are seen in the sain: ensemble. The hollow timing block is about 8 inches in length and is struck with a smooth wooden striker. The bamboo clapper is of slit bamboo with three nodes. The length of bamboo from the node to the first node has some of the material removed for the hands to hold the clapper. The length of bamboo from the second node to the third is left as it is. The clapper has a node at the top so that it will not break easily when struck. The bamboo clapper is seen in the sain: assembly, and in pot- drum and doubat troupes.
The manes of timing species are toun:, na ji, wa la' and soun. Three beats of the timing bells and one beat of the clapper produce four beats repeated produce eight beats or two common bars of notes. These two bars constitute one toun:. Three beats of the bells and one strike of the block (bamboo) constitute a bar of na ji timing. There are two na ji bars in a toun. One beat of the bells and one beat of the block constitute a bar of wa la' timing. There are four wa la' bars in a toun. The bells and block played together produces a bar of soun- si:. There are 8 soun- si: bars in a toun. Each beat of the bell in a na- yi bar has a name. The first beat is the pannet- si: because it provides the foundation. The second beat is the san- si: because it creates divisions of equal value in each bar. The third beat is the lai- si: because it follows the earlier beats. If the timing bell is not played at the first beat, the practice is called "letting go". This is usual in accompanying classical songs. If the timing bell is not played at the third beat it is called "hteik- si:". The time value of the bar may be lengthened or reduced, especially in the playing of classical music, and invariably when the song is about to end.