Altered Chord Tones

When we start playing jazz getting a good understanding of altered chords is a must, but unfortunately they can be confusing when you first see them. Here is a quick guide to altered dominant chord tones and how they work. We will use a simple C7 chord as the basis for all our alterations in this example. Perhaps I think differently about altered chords but this is my method for understanding altered chord tones.

Let’s start by taking a quick look at the chord tones in a C7 chord. The notes of a C7 chord are

C E G Bb

1 3 5 b7

We can extend the C7 chord and make it more exciting by adding extra notes to it. For example one simple way of expanding the chord would be to add the 9th to the chord creating the following chord.

C E G Bb D

1 3 5 b7 9

The 9th is a diatonic addition to the chord becuase the D note is found within the C mixolydian scale.

There are many reasons for adding alterations to a chord but the main reason is that adding altered tones to a chord makes it sound more disonant. Disonance is an important concept in jazz, as it is the build up of tension and relief that creates those lush harmonic progressions. The greater the tension a altered chord has, the more relief we feel as a listener when the chord resolves (as seen in a typical V I progression).

In reality there are only a few non diatonic notes we can add to a chord to make it sound altered. Here is a list of the altered chord tones that can be added to a chord and the notes in parenthesis refer to the notes as seen from the point of view of a C7 chord. (i.e Db is the b9 in a C7 chord).

b9 (Db)
#9 (D#)
#11 (F#)
b5 (Gb)
#5 (G#)
b13 (Ab)

The #4 and b5 alterations are the same note.

The b13 is the same as a #5 but one octave higher.

The most common place you will see an altered dominant chord is in a regular 2 5 1 chord progression. A minor 2 5 1 progression often uses the b9 alteration.

Minor 2 5 1 example

Dm7b5 G7b9 Cm

Major 2 5 1 example

Dm7 G7b5#9 Cmaj7

You can add more than one altered tone to a dominant chord to really increase the tension and jazz it up. Examples of this would be a chords such as G7b5b9, G7b5#9, G7#5b9, or G7#5#9. These chords use more than one alteration to increase the disonance within the chord. Don’t be afraid when you see chords like this as they are just simple dominant chords with a few extra notes added to them.

I hope this brief introduction helps you understand that altered chords aren’t as scary as they first appear. There are only really four possible altered notes to choose from. Adding altered tones to a chord adds a level of disonance which is integral to traditional jazz harmony.