- Also known as twelve-tone music, twelve-note music and dodecaphonic music. This is a 20th century concept mostly developed by Schonberg. A twelve-note theme is fixed upon, with each note being used once. This is known as the tone row or series. Thereafter it can appear in four main ways: forwards, backwards (retrograde), upside down (inversion), and upside down and backwards (retrograde inversion). The series can appear and begin on any one of the twelve pitches and more than one note of the series can be used simultaneously to form a chord. Serialism mostly forms the basis of a work, however, and other composers include Berg and Webern. Serialism is a feature of expressionism.?