Tertian Harmony

Creating chords by adding notes above each note of a Diatonic Scale in 3rds results in a pattern that is always the same. Every Major Diatonic scales chords have these chord qualities: Major, Minor, Minor, Major, Major, Minor, Diminished.

The CHORD quality is the result of the INTERVALS. If 1 to 3 is a Major Third the chord is a Major Chord. If 1 to 3 is a Minor Third the chord is a Minor chord. The exception is the chord built on the 7th tone. It has 2 Minor Third intervals and it is called a DIMINISHED chord.

Musicians use the Roman Numbers to communicate a songs pattern. The understand the chords found in each Key. The I chord in F is F. The V is C. In D the I is D, the V is A, and so on. Knowing Tertian Harmony makes it easy to modulate a song. This is very helpful for singers to locate the best Key to suit their vocal range.

TERTIAN HARMONY in the key of F Major, where F is I.

CHORDS built upon the DIATONIC scale in the key of F

Chord Qualities

You’ll see the name of the CHORD above the STAFF in sheet music. Since the CHORD is built in THIRDS you are able to know what notes are in it. Instrumentalists can accompany the song reading the CHORDS and improvise along with the song. This originated during the time before the invention of HOMOPHONIC music in 1600.

Accompanists would analyze the many horizontal melodies vertically and were able to name the CHORD QUALITIES that the melodies had built. A very clever and necessary skill. Today, players and writers string chords together without regard to melodies. The better players learn how to voice the harmonies in more pleasing ways, since a chord can have several positions.

The Diminished chord consists of two minor 3rd intervals, unlike other chords

Chords can continue building up in 3rds. After the the chords built on 1, 3, 5, we continue 7, 9, 11 and so on.

Musicians use this knowledge to communicate in a language of Harmony. If someone is asked to play the IV chord in the key of 4 flats, you would hear a Db Major triad. Because if Ab is I, then Db is IV, and the IV chord is always a Major chord.

N'est–ce pas?

Chord Progressions

All Pop songs have what musicians call a CHORD PROGRESSION.

In the case of simple 3 chord songs it’s usually a “1-4-5” progression.

Music theorists have actually reduced the entire harmonic analysis of a Beethoven symphony to the same structure. That’s because our type of Western Music is based on the relationship of the V (5) chord to the I (1) chord. The resolution of that harmony is called a cadence. Each note in a chord (or “voice”) naturally moves to a new note in another chord. Remember, melodies moving together horizontally create chords when looked at vertically. But actually, each voice is it’s own entity heard with the other voices- all together creating HARMONY. Today’s songwriters work backwards by first arranging a repetitive collection of chords, a chord progression, and add melody to that. A thousand years ago it was entirely different. Each voice was it’s own melody!

In Baroque music (1600-1750) you hear cadence formulas very often. As compositions developed, works became more developed. Harmonic concepts became more developed.