The Harmonic Value Of The Dominant Ninth Chord

Our focus in today’s lesson is on the dominant ninth chord.

If you give me the next ten minutes [or so], you’ll discover the secret harmonic value of the dominant ninth chord, and learn how you can harmonize the major scale with it.

Let’s take the first step by quickly reviewing the dominant ninth chord.

Review On The Dominant Ninth Chord

Here’s a breakdown of the term dominant ninth…

The term dominant in music is the technical name of the fifth degree of the scale.

The term ninth refers to an interval that encompasses nine degrees of any given scale.

A chord is a collection of three or more related notes.

The term dominant ninth chord refers to a chord built on the fifth degree of the scale, that encompasses nine degrees of the scale.

In the key of C major:

…the fifth degree of the scale (aka – “dominant”) is G:

“Let’s do some chord formation here…”

Starting from G:

…other tones of the chord can be added in thirds – tertian harmony until a ninth is encompassed.

G:

…and B:

…and D:

So far, we’ve encompassed G to D:

…which is a fifth, let’s go on…

…G, B, D:

…and F:

…and A:

At this point, we’ve encompassed nine degrees of the C major scale from G to A:

So, here’s the G dominant ninth chord:

The Power Of Dominant Chords

The dominant ninth chord is an extended dominant chord.

Considering that the basic features of the regular dominant seventh chord can be found in the dominant ninth chord, we’ll be exploring the power of chords that belong to the dominant family.

The Skeleton Of Dominant Chords

Let’s get started by taking a look at a vital part of chords of the dominant family.

The third and seventh tones of a chord are known as its skeleton. According to Jermaine Griggs, “The third and seventh tones of a chord are the most vital tones because most of the time, the quality of a chord depends on these tones.”

Using the G dominant ninth chord:

…as a reference for all other chords of the dominant family, here are the chord tones:

G is the root

B is the third

D is the fifth

F is the seventh

A is the ninth

The third and seventh tones of the G dominant ninth chord are B and F:

…respectively. The interval formed between these two tones (B and F):

…is the diminished fifth.

The diminished fifth interval is one of the harshest interval to be discovered. Musicians several centuries ago not only avoided this interval, but labelled it the devil’s interval.

This diminished fifth interval (aka – “the tritone”) is the harmonic property that chords of the dominant family have that makes them sound discordant, unpleasant, unstable, and having a tendency to resolve to a stable interval.

Chords of the dominant family are unique because they don’t belong to the major or minor category that most chords belong to. Let’s look at their unique tonal functions before we go to the next segment.

The Tonal Function Of Dominant Chords

In harmony, the strongest pull between chords is between the chord of the fifth degree (aka – the dominant chord) and the chord of the first degree (aka – “the tonic chord”), hence, what music scholars call the dominant-tonic relationship.

In every key, whether major or minor, dominant chords have the strongest harmonic pull that gravitates towards the tonic chord.

This pull is essential because in the concept of tonality, the goal is to create an attraction towards the tonic. This dominant-tonic relationship is what establishes a tonality or contradicts it during modulation.

Modulation in music is the change of key or tonality. While changing a key, you’ll have to contradict the key you’re in, and most of the time, the best chord that can contradict the key you’re in and also establish the new key is the dominant chord.

Attention: Considering that the interval between the dominant and the tonic is a perfect fifth, you can resolve all chords in the dominant family to a major or minor chord whose root is a perfect fifth below the dominant chord.

Any chord of the dominant family whose root is A, would resolve to a major or minor chord whose root is a perfect fifth below A.

So, “What note is a perfect fifth below A?” The answer is D.

So, the A dominant ninth chord:

…resolves to the D major ninth chord:

The dominant ninth chord is an invaluable chord of the dominant family.

In addition to the unique properties of chords of the dominant family, the dominant ninth chord is outstanding because it consists of all the active tones in the key of resolution.

The G dominant ninth chord:

…resolves down a perfect fifth to the C major ninth chord:

Consequently, the key of resolution of the G dominant ninth chord is the key of C major:

Just in case it escaped your notice, bear it in mind that the third, fifth, seventh, and ninth tones of the G dominant ninth chord (B, D, F, and A):

…are the seventh, second, fourth, and sixth tones of the C major scale (B, D, F, and A):

…which are also known as the active tones in the key vs the tones of the tonic triad:

…the C major triad, that are considered to be stable tones.

‘Tonic-Dominant’ Harmonization

The dominant ninth chord can be used to harmonize the major scale.

Its active tones creates a contrast with the stable tones of the tonic chord.
Alternating its tones with that of the tonic chord also enhances the sense of tonality.

The stable tones of the major scale are the chord tones of the tonic triad:

…which are the first, third, and fifth tones of the scale respectively.

The active tones of the major scale are the upper chord tones of the dominant ninth chord:

…which are the seventh, second, fourth, and sixth tones of the major scale.

Harmonization Of The Major Scale

To harmonize the major scale using the tonic triad and the dominant ninth chord, you must be acquainted with the inversions of these chords and the notes they harmonize.

The Tonic Triad

Here are the three possible ways of playing the tonic triad in the key of C major…

The first inversion of the C major triad:

…harmonizes the first tone of the C major scale:

The second inversion of the C major triad:

…harmonizes the third tone of the C major scale:

The root position of the C major triad:

…harmonizes the fifth tone of the C major scale:

The Dominant Ninth Chord

Although ninth chords cannot be inverted, however, due to the fact that we’re using the four upper tones of the dominant ninth chord [which for all intents and purposes is a seventh chord], we have the half-diminished seventh chord to invert.

In the key of C, the G dominant ninth:

…has the B half-diminished seventh chord:

…as its upper part. Therefore, let’s explore the inversions of the B half-diminished seventh chord and see the notes of the scale they can harmonize.

The second inversion of the B half-diminished seventh chord:

…harmonizes the second tone of the C major scale:

The third inversion of the B half-diminished seventh chord:

…harmonizes the fourth tone of the C major scale:

The root position of the B half-diminished seventh chord:

…harmonizes the sixth tone of the C major scale:

The first inversion of the B half-diminished seventh chord:

…harmonizes the seventh tone of the C major scale:

Put together, here’s how we can harmonize the C major scale using the tonic and dominant chords…

C:

D:

E:

F:

G:

A:

B:

C:

Attention: Take note of the alternation between C (the tonic) and G (the dominant) on the left hand. That’s what the ‘tonic-dominant’ harmonization concept is all about.

Final Words

Play through these chords severally and try to listen to the contrast between active and stable tones.

Permit me to catch my breath before sharing with you on the contrast between the dominant ninth and the dominant seventh flat ninth in another post.

All the best.

Bio
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Chuku Onyemachi

Head of Education at HearandPlay Music Group

Onyemachi "Onye" Chuku is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

Latest posts by Chuku Onyemachi (see all)

Tagged as: dominant chords, dominant ninth chords, dominant ninths, extended dominant chords, harmonization, harmonizing the major scale

The Harmonic Value Of The Dominant Ninth Chord

Review On The Dominant Ninth Chord

The Power Of Dominant Chords

The Skeleton Of Dominant Chords

The Tonal Function Of Dominant Chords