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General characteristics of harmony and tonality in the early 20th century

In the 20th century, composers thought about different approaches to tonality and harmony. A number of movements developed their own harmonic languages:

• expressionism, including serialism
• minimalism - where harmony and tonality evolved out of repeated cells
• atonal music

Some features of these styles are:

• harmonic clusters
• micro-tonality and the use of quarter-tones

Traditional and tonal harmonic patterns were also developed, such as the 12-bar blues.

Dissonance

Expressionist music was extremely dissonant. Diatonic chords were rarely used and there were very few, if any, clear cadences. Listen to Arnold Schoenberg’s Peripetie from his Five Orchestral Pieces.

Schoenberg also developed a new system to replace tonality in his music. This was called serialism. Instead of using major and minor scales, Schoenberg took the 12 tones of the chromatic scale and reordered them in any way he wanted. He would then base his composition on this rearranged tone row. The tone row would be manipulated throughout the piece - including being played backwards and upside down. An example of serialism can be found in Schoenberg’s Pierrot Lunaire.

Micro-tonality

As well as creating extreme dissonances, some composers wrote music that included microtones - intervals smaller than a semitone. The sound came across to the listener as dissonance. Quarter tones, or half a semitone, were also used. They are a type of microtone. Béla Bartók and Charles Ives both used microtones in their music. Listen to Bartók’s Sonata for Violin - ssz 117- to hear this effect.

12-bar blues

In modern popular music, tonality and harmony are simple. The 12-bar-blues chord sequence became the foundation of rock ’n’ roll music.

You can hear an example of 12-bar blues style in Bill Haley and his Comets’ Rock around the Clock.