Chord Theory

from Keyboard Guide by Jeromy Bessler and Norbert Opgenoorth Copyright 1995 by Voggenreiter Publishers. All rights reserved. Used by permission.

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Basically, any number of notes played simultaneously can be regarded as a chord. However, there are many rules concerning the actual note choice for a given chord. You should know at least some of these rules to improve your understanding and use of chords in your playing.

In traditional Western harmony, chords always consist of stacked thirds. Depending on the type of chord desired, major and minor thirds can be combined in many different ways. Starting with the basic major triad, this stacking of thirds can be continued right up to the 7/9/11/13 chord (this chord can be thought of as all the notes of a major scale played simultaneously). The number "15" is given to the root, transposed up an octave. Added notes not contained in the basic triad are thought of as "tension notes."

The numerals given to the notes of a chord derive from the corresponding major scale. For example, "3" means major third; "b3" minor third, and so forth.

Chords can be varied in many ways: you can add notes to an existing chord (e.g., the sixth), replace chord tones (e.g., use the fourth instead of the third), alter chord tones by flattening or raising them, and many combinations of the ones mentioned above. There is, however, one small problem: which combinations of chord tones sound good?

There are lots of rules on chord construction-- many of them are useful, some completely useless. Music is (and should be) a constantly evolving art form. Therefore, all of its rules are evolving, too. For instance, many of today's harmonies would have been unthinkable in the l6th century.

A thorough study of harmony and music theory in general is one of the most important ways to achieve a better understanding of what you are doing and to expand your creativity, but you should also always be aware that music only evolves by trying out new ideas. In our humble opinion, it all boils down to the simple idea of knowing the rules before bending (or breaking) them.

Today's music has been heavily influenced by harmonic concepts used in Blues and - especially - Jazz. Compared to "Classical" harmony, Jazz harmony differs in the understanding and use of consonant and dissonant chords. Jazz harmony may well be the single most important development in 20th century music theory. A thorough study of Jazz harmony and melody is one of the best methods of broadening your musical horizon and general understanding of music.

You can build quite a lot of chords from the twelve notes of the chromatic scale. Depending on your personal tastes and hearing experiences, some of them may not be very pleasant. There is, however, a kind of "common ground," a repertoire of chords heavily used in all kinds of music, even if most Rock/Pop-songs only use a small percentage of them.

For easier understanding, chords may be grouped together in "chord families": major, minor, seventh, and diminished and augmented chords. This grouping of chords into families has proven to be of great practical use.

Major chords include:
• the easy basic chords with an added sixth or ninth
• the sus2 and sus4 chord, the third is substituted by the second or fourth
• chords with a major seventh (maj7)

Seventh chords are by far the group of chords with the most members. They all contain the minor (or dominant) seventh. In traditional harmony, these chords are thought of as tension chords, meaning they have to be resolved into their corresponding tonic chord (down a fifth). Today, the dominant function of these chords still remains important, although modern composers don't consider it absolutely necessary (especially in Jazz- and Blues-related forms of music) to resolve these chords to their tonic chords.

The diminished and the augmented chord don't really belong to any of the "chord families" mentioned above, and are therefore notated separately here.
While the diminished chord consists of two minor thirds, the augmented chord consists of two major thirds. In some playing situations, another minor third is added to the diminished chord, making it a so-called diminished seventh chord.

Suggestion: There are really just three diminished and four augmented chords: you can build a diminished chord from the roots C, C#/Db and D; the diminished chord with the root Eb contains the same notes (enharmonically changed) as the diminished chord with the root C. Using the same principle with the augmented chord, you can build four augmented chords; the fifth chord again consists of the same notes (enharmonically changed) as the first.

Some chord symbols may look a little complicated at first, so here are a few guidelines for deciphering them:
• The seventh (7) is always given first in the chord symbol. It is regarded as part of the chord, not as an option (as, for example, are the ninth, eleventh and thirteenth).
• Whenever a chord contains a seventh (7) and a sixth (6), the sixth is called a thirteenth (13). This is done to clearly show the structure of the chord.
• "add"-options are added to the basic chord; "sus"-extensions replace the third of the basic chord.
• If a chord contains a b5 (flatted fifth) or a #5 (raised fifth), these altered chord tones replace the fifth of the basic chord. To show the tertiary structure of the chord, these are indicated as #11 or b13, but may be played transposed down an octave: #11 = b5 and b13 = #5.