Metric Modulations, Volume 2: Contracting and Expanding Time Within Form, by Ari Hoenig & Johannes Weidenmueller. The follow-up to Intro to Polyrhtyhms, a method for learning advanced rhythm, polyrhythm, and metric/harmonic superimposition, looks at rhythm through a magnifying glass and enables the student to see, sing and hear various subdivisions and groupings of subdivisions. This book can be used by any and all instrumentalists.