©2000 James Walker
One reason classically-trained musicians are sometimes intimidated by "jazz harmony" is their lack of familiarity with the chord symbol notation used in jazz. In fact, "traditional classical harmony" and "jazz harmony" are more similar than not, and a basic understanding of chord symbol notation will allow one to apply previously-learned knowledge of tonal harmony in a jazz context.
"Why use chord symbol notation?"
From the first week of Theory I, students are taught to analyze chords using Roman numeral analysis. This system allows one to identify the function of virtually all chords in relation to a given key.
In jazz, however, modulations and tonal shifts are far more common, and occur more rapidly, than in most Baroque and early Classical music. Consider the following harmonic example, using progressions not uncommon in jazz:
A Roman numeral analysis would quickly become cumbersome and difficult to read, whether utilizing secondary chord notation or a series of tonal centers:
Chord symbols indicate the quality of a chord, but not its function. This allows greater flexibility in moving between tonal centers, and allows a simpler (and thus, easier to read) analysis of this same example:
While the function of each chord isn't as clear as with Roman numeral notation, these chord symbols are much easier to read and decipher (at least in this case).
"How do I translate a chord symbol into an actual chord?"
Here is a common chord symbol, diagrammed to show its elements:
The root indicates just that: which note of the chromatic scale is the root of the chord. It is not, however, always the bass note of the voicing (more on that later).
The next part of the symbol indicates the quality of the chord. There are many symbols to define the quality (major, minor, dominant, augmented, diminished, half-diminished), including, in some cases, different symbols for the same quality.
The next number shows the extensions used on a chord. Classical harmony often uses only the basic triad, while jazz harmony makes greater use of the upper extensions (7th, 9th, 11th, 13th). If no extension is shown, it is assumed that the chord is a major triad. (More information on the subject may be found on this site's "ABCs of Chord Voicings" page.)
Finally, any alterations to the chord are indicated (usually within parentheses, to make them easier to identify). These alterations include raising or lowering a chord tone by half step (indicated by a sharp or a flat, respectively), and can also indicate that a given non-chord tone should be added ("add D"), or that a chord tone should be omitted ("no 3rd"). Multiple alterations may be indicated within one chord symbol ("b9/#11).
"What about inversions, or chords which don't translate well to chord notation?"
Inversions, or foreign bass tones (a bass note not found in the original chord) may be indicated with a diagonal slash, and a letter indicating the pitch to be played as the bass note:
Two chord structures may be indicated in the same chord symbol. Instead of a diagonal line, a horizontal line indicates that one triad should be voiced above the other:
The following chart shows some of the most common chord symbols used by jazz musicians, organized by sonority. The "basic mode" defines the pitches commonly associated with the chord, which provide the "base" for any alterations. A simple notated voicing of the chord is presented as a reference for each sonority.
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