Suspended Chords
A suspended chord uses a major 2nd or perfect 4th in place of the major/minor 3rd normally found in major/minor triads. Suspended chords have an abbreviated name of sus2 or sus4. For example, Csus2 is (C D G) while Csus4 is (C F G).
Contents
PreReqs
Tonality
Their sound is slightly tense but quite harmonic.
The M2 interval that occurs between the root and 2nd in sus2 and 4th and 5th in sus4 is slightly dissonant, but another way to look at it is to think of the 2 as a 9, so you have root, 5th, 9th. The 9th is a perfect 5th above the 5th, so you have basically stacked fifths.
For the sus4, the 5th can be thought of as a 4th below the root. Thus with the 4th below and the 4th above, you have stacked 4ths. Since 5ths and 4ths are the most harmonic intervals, it stands to reason that these chords will sound quite harmonic.
Also, by having neither a major nor minor third, they give little indication about whether the current tonality takes a major or minor form. Suspended chords can occur in both major and minor keys.
Inversions/Equivalence
The sus2 chord has the intervals:
R 2 5 R -M2- -P4- -P4-
While the sus4 has:
R 4 5 R -P4- -M2- -P4-
This means the chords are basically equivalent, simply using a different root note. 2nd inversion sus2 is a sus4, while 1st inversion sus4 is a sus2.
Common Shapes
6 String
| Sus2 | Sus4 |
|---|---|
2 |-|-|p| 5 |i|-|-| x |)|-|-| R |)|-|r| 5 |)|-|m| R |i|-|-| |
R |i|-|-| 5 |i|-|-| 4 |)|-|p| R |)|-|r| 5 |)|-|r| R |i|-|-| |
These are basically the same shapes as our barre chords, but with a few small differences. Either of the sus2 shape requires muting the G string. I like to use my pinky in example 1 and ring finger in example 2.
The first example of the sus2 demonstrates the stacked fifths on its bass strings. In rock playing, often only those 3 notes are played in that shape, requiring no index finger barre. The sus4 demonstrates the stacked 4ths on its A, D, and G strings.
5 String
| Sus2 | Sus4 | |
|---|---|---|
R |i|-|-|-|-| 5 |i|-|-|-|-| x |)|-|-|-|-| 2 |)|-|-|-|p| 5 |)|-|r|-|-| R |i|-|-|-|-| |
5 |i|-|-| 2 |i|-|-| R |)|-|r| 5 |)|-|r| R |i|-|-| |-|-|-| |
5 |i|-|-|-| 4 |)|-|-|p| R |)|-|r|-| 5 |)|-|r|-| R |i|-|-|-| |-|-|-|-| |
4 String
| Sus2 | Sus4 | |
|---|---|---|
2 |i|-|-|-| R |)|-|-|p| 5 |)|-|r|-| R |i|-|-|-| |-|-|-|-| |-|-|-|-| |
4 |)|-|-|p| R |)|-|-|p| 5 |)|-|r|-| R |i|-|-|-| |-|-|-|-| |-|-|-|-| |
|-|-|-|-| |-|-|-|-| 4 |-|-|r|-| R |-|-|r|-| 5 |-|-|r|-| R |i|-|-|-| |
Here we finally take advantage of that barre for the 4-string sus2 chord.
3 String
| Sus2 | Sus4 | 1st Inv Sus4 |
|---|---|---|
|-|-|-|-|-| 2 |-|-|-|-|p| 5 |-|-|m|-|-| R |i|-|-|-|-| |
4 |-|-|p|-| |-|-|-|-| 5 |-|-|r|-| R |i|-|-|-| |
|-|-|-|-| 4 |-|m|-|-| R |-|m|-|-| 5 |-|m|-|-| |
Harmonic Function
Suspended chords are often used to prolong the full resolution from a progression. For example, when resolving from V or vii° to the tonic chord of the key, the 2nd note of the key is found in both the V and vii° chords. The other notes resolve, while that 2nd sustains, forming the sus2 chord on the tonic chord, preventing a full resolution. After sustaining the sus2 long enough, the 2nd resolves up to the 3rd or down to the tonic, making the I and completing the resolution.
For the sus4, the same thing happens with the 4th note of the key, when resolving from a ii or IV chord to I. The 4th resolves down to the 3rd or up to the 5th.
Examples
G Csus2 C E--3--------3----3--- B--3--------3----5--- G--4--------5----5--- D--5--------5----5--- A--5--------3----3--- E--3-----------------
F/C Csus4 C E--1--------1----0--- B--1--------1----1--- G--2--------0----0--- D--3--------3----2--- A--3--------3----3--- E--------------------
Another common usage is to alternate between sus2, sus4 and the major or minor chord with the same root. This adds a little melody into the harmony. This can be heard most predominantly in Kansas 's "Dust in the Wind" and Led Zepplin 's "Tangerine". However, it's important to distinguish that these cases aren't often true suspensions, with the major/minor 3rd actually being played by another instrument or in a different octave. Then the effect is similar to a 9th or 13th chord, which we will cover later.
Am Asus4 Am Asus2 E E--0----0----0----0----0----- B--1----3----1----0----0----- G--2----2----2----2----1----- D--2----2----2----2----2----- A--0----0----0----0----2----- E----------------------0-----