Four of the five common seventh chord types in classical and popular music will have ninths added to them; the exception is the fully diminished seventh chord.
The \(\left.\text{}^ø{}^{7}\right.\) chord is also labeled as \(\left.\text{}\text{m}^{7}\left(\text{♭5}\right)\right.\) in jazz—\(\left.\text{C}^ø{}^{7}\right.\) is the same as \(\left.\text{C}\text{m}^{7}\left(\text{♭5}\right)\right.\).
In lead-sheet notation, adding “9” to a chord symbol means the 7th is also present.
“9” is “2” an octave higher and always comes from the major scale unless otherwise specified.
Alterations (maj, \(\left.\text{}{\Delta}\right.\), ♯, ♭, \(\left.\text{}{+}\right.\), m, –) are applied as follows:
“maj” or “\(\left.\text{}{\Delta}\right.\)” followed by 7, 9, 11, or 13 means the 7th of the chord is major, not the 9th, 11th, or 13th.
Lowercase “m” or the minus sign (“–”) means minor and applies to the 3rd of the chord.
The minus sign (–) is equivalent to a flat when placed in front of 9, 11, or 13 (i.e., ♭9 and –9 mean the same thing). “\(\left.\text{C}^♯{}\right.\)–\(\left.\text{}^{6}\right.\)” (equivalent to “\(\left.\text{C}^♯{}\text{m}^{6}\right.\)”) means a \(\left.\text{C}^♯{}\right.\) minor chord (“\(\left.\text{C}^♯{}\right.\)–”) with the 6th from major (A♯). “\(\left.\text{C}^♯{}\right.\) (add –6),” which is equivalent to “\(\left.\text{C}^♯{}\left(\text{add ♭6}\right)\right.\),” means a C♯ major triad with the ♭6 added
The plus sign (\(\left.\text{}{+}\right.\)) can mean “augmented triad” or is equivalent to a sharp when placed in front of 9, 11, or 13. C\(\left.\text{}{+}\right.\)7 means a C augmented triad (“C\(\left.\text{}{+}\right.\)”) with a minor seventh from the root to the seventh(“7”), not a C major triad with a major 7th.
Chromatically altered chord numbers (affecting 6, 9, 11, 13) are usually set apart by parentheses so as to clearly designate whether the minus, plus, or sharp, or flat is affecting the chord or the added note. For example, consider C♭9 versus C(♭9) versus C7(♭9).
If a chord has a 9th but no 7th, use the term “add 9.” In popular music, sometimes “2” or “add 2” is used instead (refer to the Chord Labels section).
m\(\left.\text{}{\Delta}\right.\)7 Chord: In addition to the five common seventh chord types, jazz includes use of the minor-major seventh chord (a minor triad with a major seventh). This chord will commonly have a ninth added as well. You will see the “major” symbol (\(\left.\text{}{\Delta}\right.\)) used primarily in jazz. Popular music typically uses “maj” instead.
11th and 13th Chords: 11ths and 13ths always come from the major scale unless otherwise specified. (“11” is “4” an octave higher and “13” is “6” an octave higher.)
All numbers up to the highest number are assumed. C9 means that the 7th is also included below the 9th. C13 means C–E–G–B♭–D–F–A—everything up to the 13th. For this reason, we will use C9(13)—to specify C–E–G–B♭–D–A—instead of C13, which would be used in the real world to describe these notes. In the real world, a composer or arranger writing C13 will assume the pianist or guitarist knows to omit the unaltered 11th because it clashes with the major 3rd of the chord. In this music theory course we will be specific as to which notes are included and left out.
\(\begin{smallmatrix}6\\9\end{smallmatrix}\) chords: If a chord has a 6th and a 9th, call it a \(\begin{smallmatrix}6\\9\end{smallmatrix}\) chord (C\(\begin{smallmatrix}6\\9\end{smallmatrix}\)) instead of a \(\begin{smallmatrix}9\\6\end{smallmatrix}\) chord. The major \(\begin{smallmatrix}6\\9\end{smallmatrix}\) uses the major third (C–E–G–A–D) while the minor \(\begin{smallmatrix}6\\9\end{smallmatrix}\) uses the minor third (C–E♭–G–A–D). The “6” always comes from the major scale unless otherwise specified. (Refer to the Chord Labels section for examples.)
Enharmonic respelling: Jazz musicians will sometimes respell double-flatted notes and double-sharped notes enharmonically because for some musicians theory was viewed more from the aspect of the piano than the staff. This may at times include enharmonically respelling notes like B♯, C♭, E♯, and F♭ (although these notes sometimes will be used).
For the purposes of this text, we will assume the bass note is the root when analyzing chords. While slash chords (E/C, for example) are used in jazz, this chapter is meant as an introduction to the fundamentals of jazz harmony and therefore will not include the use of slash chords.
