It is formed by adding bouncing beat per minute to each hand on the basis of double jumping and rolling. That is, after the wrist action is used to drive the drum stick to play once, the elasticity of the drum stick after hitting the drum surface is effectively controlled and adjusted, and it is played for three or more times. Its requirements are the same as that of roll opening, and the knocking effect is also required to be uniform, smooth and stable. In contrast, dense rolling focuses more on the word "dense". That is to say, the gap between sounds is smaller and the bouncing particles are faster. The difficulty is that the strength of multiple particles in each hand should be uniform, and there should be no sound head to avoid lasting wave ups and downs.

Dense rolling can be carried out in the following ways:

(1) The first stage of uncontrolled multi-jump exercise: lift the drum stick as high as possible with the left and right wrist movements respectively, and then let the drum stick naturally fall to the drum surface to make it bounce naturally until it stops completely. You don't have to worry about how many times the drum stick plays on the drum surface, and you don't have to try to control it. Arms, wrists, palms and fingers must be relaxed as much as possible in order to make full use of the natural elasticity of the drum stick after hitting the drum surface. Care should be taken to avoid holding the drum stick too tightly, so as not to inhibit the natural bounce of the drum stick, resulting in stiff arms, wrists and fingers. This will reduce the number of bounces and squeeze the sound.

(2) The second stage of controlled smashing and bouncing practice: after mastering the elasticity and full bouncing of the drum stick on the drum surface, you can control the number and balance of bouncing with the help of appropriate pressure from your fingers and wrists. For example, your right hand bounces twice to three or four times ... it's best to bounce a dozen times at most, and then practice your left hand in the same way. Through practice, the number of times the hands bounce is exactly the same, and the sound of bouncing and hitting is unified with the sound of using wrist movements.

(3) The third stage of alternating practice of left and right hands: After breaking up and mastering the method of compound jump, you can practice multiple jumps with both hands alternately and in a controlled way. At the beginning of practice, the speed should be slower, and attention should be paid to the smooth connection of hands to avoid the phenomenon of incoherence, stress and low voice in the connection of hands. The big arm should be relaxed as far as possible, and the left and right hands should be connected continuously to achieve the linkage effect, so that there is no gap in the rolling connection between the left and right hands.

(4) The fourth stage is to practice scrolling with different time values: that is, to play scrolling with rhythmic time values. First, alternately play the sixteenth notes in the 1~4 beat with both hands, and then alternately play multiple jumps at the same alternating frequency. The frequency of alternating hands should depend on the speed of work. Different speeds should be played in different ways. In order to accurately play the rolling notes with different speeds and durations, we can take various rhythm patterns as the basic rhythm framework and practice them repeatedly. The ultimate requirement is to achieve a uniform and stable long sound effect.