How did Henry Cowell’s tone clusters challenge traditional harmonic analysis?

Henry Cowell’s tone clusters—chords produced by simultaneously depressing several adjacent keys, often with the forearm—challenged traditional harmonic analysis because they could not be interpreted as functional harmony.12

In traditional Western harmony, chords are constructed through the superimposition of intervals of a third, forming structures like triads that imply specific harmonic functions and resolutions. Cowell’s clusters, which he later termed secondal harmonies because they are based on the interval of a second, eschewed these established rules. Because these clusters function as dense blocks of sound rather than as chords with traditional tonal relationships or directional logic, they defy analysis within the common practice system.312

By prioritizing these sonorities, Cowell helped shift the focus of composition away from traditional harmonic organization toward new methods of musical structure, contributing to the broader 20th-century dissolution of the harmonic system that had prevailed for centuries.2