Many classical audiences cringe at the thought of 12-tone music, yet it’s one of the most influential system of the 20th century.

What is the 12-tone technique?
 It’s a compositional method whereby the 12 notes in the chromatic scale (all keys on the piano in one octave) are organised into a specific order called a tone row. The system was developed after WWI by Arnold Schoenberg, who believed no single tone should be more important than any other in a composition. Each of the 12 notes must be sounded before the tone row can be repeated. Since no notes are favoured over others, the music isn’t in any key, making it truly atonal.

Wouldn’t it have made sense just to write freely atonal music rather than following such strict rules?
Not necessarily. Earlier works such as Schoenberg’s Pierrot Lunaire (1912) and Berg’s opera Wozzeck (1922) used free atonality to express the characters’ madness. Composers soon realised how difficult it was to create structure without any harmonic boundaries at all. Schoenberg believed use of the 12-tone system would bring order to his work and restore the structured discipline of classical music. He also predicted the 12-tone system would ensure...