(Percussion). In Drummer's Polymetric Mastery, educator, author and performer Jason Gianni, provides an in-depth study of independence aimed at uncovering a pathway to executing polymeters, over-the-bar phrases and cross-rhythms for the drum set. Based primarily around groove-building exercises in 4/4, Jason's unique approach exposes a systematic process to develop the various subdivisions and odd-numbered grouping coordination required in understanding the language of polymetric drumming. The material throughout the book is presented through both standard groove options and assorted rhythmic exercises for bass drum & snare drum, combined with accented ostinato hand patterns to assemble technically demanding yet innovative contemporary patterns. Despite an understandably greater level of difficulty, the progressive pathway presented in the book is suitable for those just entering this adventurous journey up to drummers who may have already developed an appreciation of polymeters. Each section helpfully guides the performer with suggestions on how to read, hear, count, perform or even transcribe the exercises. With the aid of selected video examples, the comprehensiveness of the material provides the reader with the opportunity to come away with a much more controlled sense of numbers heard simultaneously existing with one another; a sense of "rhythmic ear training." Venturing into a more challenging field of study will, in turn, secure a better command of control & solidity of a more simplistic, standard internal pulse as a result. In addition to a much higher level of interdependence gained, this material will open the door for the drummer to discover his or her greater potential for individuality and creativity.