Ninth Chords

1. Revisiting Tension Chords

In the article “Seventh and Tension Chords” in Chapter I, we learned about adding notes to introduce complexity to the sound.

Back then, even the concept of adding 7^th was unfamiliar. Now, we’ve come to know about seventh chords, sixth chords, as well as new types of transformed chords like sus4, aug and dim. It’s time to delve deeper into the theory of adding notes!

Add or Transform

For those who have been experimenting with various “adding notes” since learning it in Chapter I, you may have encountered similar-sounding chords in the first half of Chapter III. However, the transformed chords covered earlier have a different approach than tension chords. Those transformation involved a change in the original chord tones, leading to the elimination of one of the original chord tones.

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For example, sus2 is intended to be used in a way that creates tension by not playing the 3^rd and resolving when the 3^rd is played. So, when a band member says, “Let’s use sus2 here,” it automatically carries the nuance of “We want to create suspense, so don’t play the 3^rd.”

However, there are times when you simply want to add the 2nd note to a major chord to introduce some complexity.

This session focuses on the methodology of “adding” notes rather than “shifting” them. It’s just like when we evolved from triads to seventh chords. Please proceed with this awareness of the difference.

2. What is a Ninth Chord?

Now, let’s add the 2^nd note. This is a traditional approach already found in classical theory. However, they didn’t think of adding the “2nd”. Instead, they considered building on the triad (1-3-5) and adding the 7th, then adding one more note above that, calling it the “9th”.

Just as chords built up to the 7^th are collectively called “Seventh Chords”, chords built up to the 9^th are collectively referred to as Ninth Chords.

Octave Position Irrelevant

Even if the 9^th note is positioned just above the root and its interval is actually 2^nd, it is still called a “ninth chord”, ignoring octave differences.

This is similar to how the octave placement of C, E and G in a C Major chord doesn’t affect the chord name––The chord symbol system ignores octave differences.

11th, 13th

By repeating the “BBQ stacking”, the 4^th note appears as the “11th,” and the 6^th as the “13th.”

These notes are also utilized in popular music. However, the theories around 11^th and 13^th can be quite complex. Since we’ve just learned about sus4 and sixth chords, this time we’ll focus on the 9^th only. We’ll cover the rest of them in Chapter IV. Until then, please still try to experiment without chord names, referring to the “Seventh and Tension Chords” article.

3. Types of Ninth Chords

When adding 9^th along the scale, it often falls on the pitch of the “major 9th”, a whole-step above the root. Therefore, the chord naming system is also primarily designed with the major 9th in mind. When adding the major 9th, it’s as simple as replacing the “7” with “9”.

If based on a major seventh chord, it changes from “Δ7” to “Δ9”, and if based on a minor seventh chord, it changes from “m7” to “m9”. Very simple! I won’t introduce “minor 9th” for now, as it involves more advanced concepts.

Dominant Ninth

By the way, the chord with the symbol “9” also has an alternative name, Dominant Ninth, This is to distinguish it from the general term “ninth chord” that refers to all types of ninth chords, similar to when dealing with seventh chords.

Prime Chords and Ninth Chords

When adding the “major 9th” to the six prime chords, only III_m requires an accidental symbol.

Since the note whole-step above mi is fa^♯ instead of fa, the III^m chord is special on forming ninth chords, and caution is needed when using it, as it deviates from the original scale. As a matter of course, when the melody uses natural fa, it’s advisable not to add this note.

Caution with IIIm9

It was mentioned that a note or a chord that follows the key’s scale is explained as being “diatonic to the key”. However, the 9^th note in the IIIm chord is not diatonic. Using it as the top note in a melodic line or accompaniment may create a delicate situation, as it might suggest modulation or other uncertainties. Therefore, a common practice is to incorporate it subtly within the accompaniment to make it less conspicuous.

Although not reflected in the chord name, this is an essential aspect. The vertical arrangement of chords is referred to as “voicings“. Clever incorporation of non-diatonic notes can result in unique and captivating sounds, even if those notes are not originally in the key.

4. Sound of Ninth Chords

Let’s compare how the sound changes between seventh chords and ninth chords.

IV_Δ7II_m7VI_m7I_Δ7III_m7

Here we have the familiar seventh chords. There’s no doubt that they have a richer sound compared to triads, but after sticking with them since Chapter II, they might start to feel a bit boring to us, the masters of chord types…😎
That’s where the ninth chords come into play.

IV_Δ9II_m9VI_m9I_Δ9III_m9

While it may not be as dramatic a leap as from triads to seventh chords, the addition of the “muddy” tones 9^th as well as 7^th introduces more complex sounds. Especially the last chord III_m9 exudes an unmistakably unique atmosphere, with its added accidentals.

Non-Prime Chords and 9th

Outside of the prime chords, adding 9^th works well with secondary dominants like I₇VI₇, as well as parallel minor chords like IV_mV_mVII. Especially in jazz-influenced songs, the muddied sound of 9^th fits perfectly.

II_m9III_m9VI_m9V_m9I₉

While this is a classic chord progression, adding 9^th gives it a more sophisticated touch. Compared to the mellow sound of 7^th, it feels to me that 9^th introduces a slight “sharpness” and “floating” sensation.

5. add9

As seen so far, a ninth chord is a “Five-story building”. When using chord names like “Δ9” or “m9,” the seventh note is automatically included, even though the number “7” is deprived.

Therefore, if you want to add only the 9^th note without the 7^th, there is another notation called “add9“. Alternatively, using parentheses like (9) is also an option, which is sometimes adopted especially in the case of sixth chords.

The add9 chord frequently appears in guitar playing. Due to the structure of the guitar, the add9 chord can be easily played by making slight finger adjustments from the regular chords, incorporating open strings.

The add9 chords, by not including the seventh, have a slightly restrained dissonance, making it well-suited for distorted guitar timbre. As a result, you can frequently find add9 chords in rock songs.

9th-Related Chords

Sus2, 9, Δ9 and add9. These four can be confusing to distinguish.

Sus2 doesn’t have 3^rd. Add9 doesn’t have 7^th. For “9” and “Δ9”, recall the distinction between “7” and “Δ7”.

Once you’ve mastered 9^th, in Chapter IV, you’ll delve into the realm of 11^th and 13^th.

Summary

• The chord formed by adding the ninth tone to the seventh chord is called the “Ninth Chord”.
• For chord naming, simply replace the 7 with 9 based on the state of the seventh chord.
• Mastering the use of non-diatonic tones, such as in IIIm9, requires careful attention to voicings.

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