Often times when playing a tune we want to delay the resolution of a chord progression. This delay creates an emotional moment, by leaving you hanging on, anticipating the resolution of the chord. Suspended chords are a great way pull this off.

So, what is a sus chord? Sus chords, short for suspended, are chords where the 3rd has been altered slightly to sound pleasant, but unresolved. Most commonly, suspended chords raise the 3rd to the 4th, but it's also common to drop the 3rd to the 2nd.

I like to think of suspended chords as consonant sounding, but not resolved. Like a dominant chord, they create a tension which is resolved to the root chord on the same note.

They are commonly used as substitute chords for the ii or the V7.

But unlike a dominant chord, the suspended chord doesn’t have a gravitational pull that forces the resolution. Rather, suspended chords have a floating feeling, as if they have been, well, suspended off the ground. As such, this sound is often used without a resolution, simply for this unique quality on its own.

The Classical Sus-4 Chord

In classical music, suspended chords are used to hold back the resolution to the final chord. Commonly, classical musicians call this a “sus 4” chord, because it’s replaces the 3rd of the chord with the 4th. That suspended chord is traditionally held briefly, to allow the listener to anticipate, and thus appreciate, it’s resolution.

Expanding the Suspended 4th to a slash chord

The classical sus-4 chord is a little thin sounding for modern jazz. Jazz musicians love to fill their chords chock full of notes. For suspended chords, we do that by voicing them as a slash chord.

To do this, we play the root of the suspended chord in the left hand, but we play a major chord a full step lower in the right hand. ie. for a Gsus chord, you would commonly play a F/G.

Also common is to play a minor 5 chord over the root. ie Dmin/G. This is almost identical to the F/G listed above — 3 of the notes are the same — but with the 5th added in the left hand.

In order to accommodate different melody notes, you can play inversions of the right hand chord. Here's an example with the F/G in first inversion:

Are suspended chords major or minor?

When used to create motion from a tension to a release, a suspended chord can work equally well resolving to major or minor. Because of the half-step between the 4th and the major 3rd of the chord, the motion is a bit stronger in major keys. But, it’s used all the time in minor as well.

But, when a suspended chord is used as it’s own consonant chord, without an immediate resolution, its neither major or minor in quality. In that case, it’s quality is perhaps simply “suspended.” A sound of its own.

Does the 4 always replace the 3?

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.

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