English to Russian Other Music drumming

Alfred Music Publishing bring us Jeffrey W. Johnson’s ‘The Level System’, which is described as ‘a natural drum technique method for developing control of accents and dynamics’.
Many studies on stick technique exist, from Moeller to George Lawrence Stone, yet much of these studies can seem at times daunting and too academic to be accessible to the student drummer.
The goal of these technical studies was to examine the relationship between movement and sound. As Johnson writes; “(Technique)…itself when referenced to drumming is the ability to direct the sticks using the energy provided by the hands along with the facility to control and manipulate the stick after the rebound has occurred. Through the use of this book, the drummer will learn to work with the body not against it.” Ultimately these technical studies empower the drummer to play with fluidity and consistency throughout their playing with minimal psychical exertion.
Many student drummers will come across these studies within the first few years of playing yet not truly understand them until much later. The often convoluted nature of these studies can deter students from fully understanding and exploring these methods at the early stage of learning when they are most relevant. Jeffrey W. Johnson has in this book combined key elements of the aforementioned studies and presented them in a way that bridges the gap between the academic and the core components.
Focusing more so on the system taught by George Lawrence Stone and Joe Morello, ‘The Level System’ sets out these concepts in a user friendly and easily digestible format.
The book begins using clear diagrams to explain the basic starting positions of the hands relevant to the consequent exercises. It then sets out the four component strokes which are integral to the application of this technique/level system. ***Full, tap, up and down strokes*** are explored using various rhythmic exercises before combining the strokes using varying dynamics. It is the depth in which dynamics are explored which really sets this book aside from other stick technique studies.

Речь идет об учебном пособии для начинающих барабанщиков.
C full и tap понятно, но вот что такое up/down striokes?