Jazz Theory and Practice Module 5 a, b, c Dim. 7 th & 9 th Chords; Extensions to the 13 th ; Other Harmonic Structures B. Extensions: 9 th, 11 th and 13 th chords Jazz Theory and Practice Harmonic extensions are notes added to the chord in the second octave beyond the 7 th. In our study of jazz harmony we can easily find labels for all of these chords with added extensions, but in common performance practice among jazz musicians there are often wide-ranging differences between the theoretical chord definition, and the actual chord that emerges in performance (written or improvised): In the large repertoire of sheet music and lead sheets the harmony is typically from our previous study: almost entirely added-6 th and 7 th chords. Many melodic lines, however, contain implied extensions. To keep the notation simple a basic dominant-7 th chord might be suggested, but certain notes in the melody, especially notes of longer duration or on a strong beat will become extensions. Over a C7 chord, for example, a D becomes a 9 th, or an A becomes a 13 th. (but not an added-6 th if the 7 th is present!) Many performers will routinely add extensions to 7 th chords whether they are notated or not. This happens not only with the harmony providers (keyboard or guitar), but good horn players will include extensions within improvisations. The practice varies widely according to style and taste, but extensions to the V7 chord (9, b9, #9, 13) are very common, and a final I chord is often decorated with virtually any combination of extensions. This practice is so widespread that many arrangers assume that the performer will add to the harmony; another practiced freedom in jazz interpretation! Although it would seem that the practice of extensions is about adding notes to the chord, in fact subtracting notes is almost more important. 2016 Peter J. Clements 1
The subtraction happens in two ways: (1) often during performance some notated extensions are omitted for practical reasons, and (2) an extended chord is almost never complete : a 13 th chord theoretically contains 7 different notes, but in practice 5, 4, and even 3-note voicings are typical. The voicing of extended chords is an essential skill for a good jazz performer, especially pianists, guitarists, and arrangers. The 9 th, 11 th, and 13 th are all extensions, and are often regarded as the outer limits of the jazz harmonic language, at least for chords built of thirds. This is tertian harmony; there are other basic harmonic structures used in jazz (especially quartal harmony: chords built of 4 th s). Notice, in the following example, that once the 13 th is added to the chord all seven notes of the scale are represented. The next added third beyond the 13 th is the 15 th, which is the root, so isn t really an added note at all; there is no 15 th chord! 5b1 This example shows extensions to both the major 7 th and the dominant 7 th chords, and how they are identified. The 11 th chord has been omitted: with a major triad on the bottom the 11 th is almost never used, because the major 3 rd combined with the 11 th produces a strongly dissonant minor 9 th interval. In both 13 th chords shown the 11 th would almost always be omitted in the voicing. These towers of notes are certainly intimidating, but, in fact, are almost never played that way by a keyboard or guitar player. In the previous section we encountered examples of 9 th chords using rootless voicing; similar reductions are applied to 11 th and 13 th chords. Voicing becomes a major issue with extended chords; each extension has its own rules. The 13 th is actually a 6 th above the root of the chord, and, in fact, all the extensions can be regarded in a similar way: the 11 th is a 4 th above the 2
root, and the 9 th is a 2 nd above the root. With reduced voicing, then, can a 13 th chord ever be the same as a chord with an added 6 th? Look at the following examples of chords with extensions, as compared with chords that simply have an added note in the first octave: 1. 2 nd s and 9 th s: 5b2 The C2 chord (or C(sus 2))is unusual, and, without a third, could be heard as either major or minor. All the rest are true 9 th chords; notice that the two add 9 versions are missing a 7 th, so the 9 th is added to a triad. The two 6/9 chords are very common, usually voiced in a reduced form. In module 5a there were various examples of rootless voicings for 9 th chords. Remember that 4-note versions usually look like common 7 th chords; for 3-note versions, the three essential notes are the 3 rd, 7 th, and 9 th. Look at the following examples: 5b3 3
There are many instances in the above examples, especially among the 3-note voicings, where another label could easily be applied: the Dm9 looks like an Fmaj7, the Gm9 looks like a Bbmaj7, etc. Realize, however, that other chord notes could be in other parts, especially in the bass. There are frequent examples where a composer/arranger might label a chord as a 9 th chord, but add other notes for colour, especially the 13 th : 5b4 Because each chord contains a 7 th, the extra note is a 13 th, not an added 6 th. The final example is labelled as a Gmaj7, but contains both the 9 th and the 13 th! This is a typical contradiction between jazz theory and jazz practice. These voicing examples are all taken from actual keyboard parts, either written for a small jazz ensemble or a big band. 2. 4 th s and 11 th s: 5b5 Beginning with a major triad, virtually every chromatic note in the octave can be added to the chord as part of an altered chord or extension, except for one note: the Perfect 4 th above the root. Sometimes the 4 th is called the avoid note ; if it s added to a major chord, or even just given too much emphasis in an improvisation it really sounds wrong. Given the right context, however, a 4 th may be added to a triad, 7 th, or 9 th chord, with the 3 rd omitted. These chords will have sus added to the label; an 4
abbreviation for suspension. In classical harmony the suspension is a very common musical device. It s always on a strong beat, and creates tension because it temporarily replaces a chord note, then moves down one step to the chord note to release the tension. The most common suspension is the 4-3 suspension: 5b6 In jazz harmony the suspension sometimes resolves (moves down a step to the 3 rd of the chord), but just as frequently doesn t resolve at all; in this case it s really an added 4 th, not a suspension, but is always labelled as sus in common practice, and the 3 rd is almost never included in a sus chord. (Is it major or minor?) As mentioned earlier, the true 11 th (octave + P4 th ) is seldom used with a major chord where it clashes with the 3 rd an octave below. In the examples above the 11 th is used with a minor chord below, producing a major 9 th against the 3 rd of the chord, a much softer dissonance than it would be with a major chord. The next example shows the #11 used with various major chords, producing that same softer major 9 th against the 3 rd below. 3. Sharp 11 th s 5b7 The #11 is a common extension, and is almost always used with a major chord. It does add a particular colour to the chord which is easily recognized: the tritone (augmented 4 th ) against the root below. Full 11 th chords contain six different notes, so are almost never played that way. 5
Look at the following examples; for either 11 th or #11 th chords the essential notes are the 3 rd, 7 th, and 11 th. For a simple sus chord the root, 4 th, and 5 th are essential, but sus chords often appear with added 7 th s and 9 th s as well. In the first two #11 chords in the example below, the #11 is spelled enharmonically. 5b8 4. 6 th s and 13 th s: 5b9 13 th chords actually appear quite often, even in pieces with few extensions where most of the harmony is 7 th chords. This is true in 19 th century Classical music as well, where the V13 often appears as a dramatic climax at the cadence. It can almost be assumed that, whatever notes are omitted from the 13 th chord, the 7 th should always be there; this clearly produces the 13 th sound, which is entirely different from an added 6 th chord. For the 13 th chord the 7 th and the 13 th are essential notes, as well as the 3 rd to identify the chord as major or minor. Here are some sample voicings for the 13 th chord: 6
5b10 There is much to be learned from studying these examples, all taken from jazz ensemble keyboard parts. The first three examples include the three essential notes as well as the root in the first example, the 9 th in example 2, and the flatted 9 th in example 3. In example 4 the root is added, and the 5 th is added as well in example 5. Example 6 is unusual because the 13 th is now below the 7 th, producing a dissonant minor second. Examples 7 and 8 add the 11 th for the first time, but it s the #11 to avoid a strong clash with the 3 rd. If the C were used here there would be two major 7 th /minor 2 nd intervals in the chord. The final two examples do introduce the natural 11 th to the chord, but it s disguised with the sus label which means the 3 rd has been replaced no clash! In these examples, as well as previous ones in the lesson, there is a common principle in all the various voicings: The extensions are never in the bass; but always in the upper voices. This is only logical: the 11 th s need a root or third below; the 13 th almost always has the 7 th below. 7
Something to listen to: The Boy (or Girl) Next Door has two #11 chords in the melody of the first phrase, setting the character for the piece. Find one of the several versions by Frank Sinatra; some versions include the verse at the beginning. Chelsea Bridge by Billy Strayhorn also has prominent #11 s in the first phrase, and other extended chords throughout the piece. Check out the 1961 recording by the Duke Ellington Orchestra. Take the A Train by Duke Ellington. The famous piano introduction is built around a D7(#11) chord, which returns in the tune. Look for the Ellington version. There are dozens of contemporary big band arrangements from the past 10 years that feature the harmonic language of extensions and sus chords. Check out Mossman s Samba Kinda Mambo; there are several good performances by high school and college bands. 8