During the Baroque and Classical periods, major and minor triads were considered consonant, and the dissonant intervals of seconds, fourths, and sevenths required resolution
This changed just before the turn of the 20th century when French composers Debussy, Satie, and Ravel added unresolved sixths, sevenths, and ninths to color triads. These harmonies sounded exotic at first, but over time listeners embraced them as colorful and beautiful.
Play the following chords on the piano and listen carefully to the differences in sonority:
These chords all function as tonic in the key of C major, but each has a unique color.
Typically, diatonic chords in jazz tunes have at least four notes:
In tonal jazz harmony, predominant — dominant — tonic progressions remain intact, but the chords have more color tones than the triads and seventh chords from the common practice period. Jazz harmony embraced more color tones as its harmonic language evolved from the 1920s through the 1960s.
A simple cadence resolving to a triad:
Early jazz harmony incorporated added major 6ths:
The D7 is a secondary dominant, the subject of the next Playing Changes article.
In the 1930s, major sevenths and major ninths become more common:
More color tones appeared throughout the 1940s and 50s, paving the way for the modal jazz revolution:
Internalizing the sound and function of harmony based on triads and seventh chords give us a foundation to approach the rich language of jazz harmony.