How Sus Chords Work and When To Play Them

Suspended chords can be intimidating when learning to play jazz from a lead sheet. You may be familiar with the sus4 which was so prevalent in classical music, but aren't sure how to handle it in the jazz context.

So, what is a "sus chord?" Sus chords are major or minor chords where the 3rd of the chord is replaced by the 4th. Jazz players think of this as a ii chord over the root of the V, such as G-7/C.

The sus-4 chord from classical music #

In classical music, suspended chords are used to hold back the resolution to the tonic chord. Classical composers carefully setup tension in need of resolution, and just when you think the resolution is about to arrive, they delay it one last time with a suspended chord.

This is achieved by removing the 3rd of the chord, and replacing it with the 4th:

This chord doesn't create much tension on its own. In fact, it's rather consonant sounding. But at the same time, it's not resolved either. It "floats" out there as if needing to be grounded.

This suspended chord is traditionally held briefly, to allow the listener to anticipate, and thus appreciate it’s resolution.

While the sus chord in this context does imply its resolution -- a Gsus wants to resolve to a G major/minor chord, it doesn't have exceptionally strong gravity to pull it there like the dominant chord does. Instead, the composer uses the sus chord as one of many devices throughout the piece to drive the piece home to the tonic.

How sus chords are used in jazz #

Much like in classical music, sus chords in jazz delay the resolution of a chord. But, unlike classical music, that chord resolution is not as often the tonic chord. It's very common, for example, for a sus chord to resolve to a dominant 7th chord.

The following example shows a few sus chords resolving to dominant chords, following the circle of 5ths.

Don't get too caught up in the voicings used here yet -- we'll get into that in a minute -- but look carefully at what changes between the sus-chord and the dominant 7 that follows. In each example, there's 1 note that moves, the 4 to the 3.

A sus chord acts as a transition for ii-V progressions #

The sus chord has a lot in common with both the minor-ii, and the V7 chords.

The following example in the key of C demonstrates this:

• The ii and V-sus chords share all the same notes except the root
• As demonstrated previous, the V-sus and V7 only differ by the 4 resolving down to the 3.

Take a look at the following example of a ii-V progression in C using simple 3-note voicings.

In the ii-V in first measure, two notes move at the same time. The 7 in the ii chord resolves to the 3 of the V7, and the roots change.

In the second measure the same notes move, but we move them one at a time. This creates an intermediary chord -- the sus chord.

A sus-chord delays a V-I (or V-i) #

In the same way a sus-chord can sit between a ii and V, it can also simply precede the V chord even when the ii isn't used.

Try this anywhere you encounter a V-I cadence, it creates some nice inner movement between your voicings.

A sus-chord transition for a ii-V-I #

If you take these ii-V and V-I progressions and combine them, you can turn an ordinary ii-V-I progression into a smooth ii-Vsus-V7-Icadence:

For some extra movement in this cadence, try altering the extensions of the dominant 7 chord, as I did with the following G13b9 chord:

Other uses of sus-chords #

As we've discovered together, the sus-chord bears a lot in common with a ii and V7 chord. Not only can the sus provided a seamless transition between those chords, but it can also act as a substitute for either.

Experiment by playing through some of your favorite tunes, but substitute some of the dominant and secondary dominants for sis-chords instead. It keeps a similar feeling to the original, but adds some nice color.

In more modern jazz (hat tip to Mr. Herbie Hancock) the sus-chords stand alone as their own sound, rather than as a substitution or point in a cadence. Check out a recording of Maiden Voyage to hear these sus-chords in action.

How to voice a sus-chord on the piano #

There are a few typical ways to voice sus-chords at the piano. We'll start with classical triads, and then move into more sophisticated jazz voicings.

Voicing a sus-chord the classical way #

The following is a bit of a cliché example of a classical voicing, but it demonstrates the way composers before us thought about suspended resolutions. You may not encounter this exact phrase in Bach chorales, or Beethoven sonatas, but you will find very similar phrases.

Voicing a sus-chord as a slash chord #

When I first learned my jazz sus-chords, I learned them as a slash chord. I've seen this taught two different ways, but they are so similar I think of them as practically the same.

• Play the root of the sus-chord with your left hand, and a major triad a whole step lower. (G in the bass, and anF-Major triad in the right)
• Play the root of the sus-chord with your left hand, and a minor-7th chord a fifth below. (G in the bass, and anD-7 in the right)

You can take this a small step further by changing the left hand to be a dominant 7th chord (I usually use a shell voicing) instead of just the root note. This creates a more full version of the slash chord as a polychord.

Voicing a sus-chord with the major 3rd included #

In the original classical sense, suspended chords would replace the 3rd with the 4th, this sets up the resolution, where the 3 comes back replacing the 4.

But that doesn’t have to be the case. There are many examples of jazz musicians voicing suspended chords with the 3 included.

Notice how in this example the 3rd (B) is voiced higher than the 4th (C). The voicing is more consonant this way. That’s not to say you can’t voice it with the 4th on top, it’s just a bit less orthodox.

What scale to play over a sus-chord #

There are a number of approaches we can take to improvise over a sus-chord. Arpeggios and scales both work great. It's especially important to emphasize the 4 resolving to 3 in your lines.

As scales go, you have a couple basic choices to start from:

• Major modes: Use the mode for the chord your sus-chord is resolving to. For example:
  - Csus resolving to Cmaj7 would use the Ionian mode (major scale).
  - Gsus resolving to G7 would use the Mixolydian mode.
• Substitutions: When the sus-chord is used as a substitution, play any scale that would also work for the chord being substituted.
• Pentatonic scale: Use the major pentatonic scale which starts a 4th above the root of your sus-chord. Importantly, you should be careful using the major pentatonic based on the root of the chord, as it features the major 3rd.

When worked fully into your fingers, sus-chords can add great movement and variety to your playing. Practice them until you know them inside and out, and you'll find yourself crafting elegant cadences within your tunes.