Specifically, I want to examine the following:
- Suspended chords
- Fourth Chords
- Polychords
Suspended Chords
We come across suspended chords in two forms, one common in rock/pop music (though it also occurs elsewhere), the other mainly appearing in jazz.The Suspended Fourth and Suspended Second chords
Consider the following two chords:
The one on the left is a C suspended fourth chord (Csus4). The one of the right is a C suspended second chord (Csus2). In both cases, we have replaced the 3rd with another note, either the 4th or the 2nd.
The effect of this is to create a chord that sounds like it's waiting to shift into something else. Changing the 4th (or 2nd) to the 3rd (major or minor) resolves the chord. This is actually a very old idea, musically, going all the way back to the Renaissance.
In modern usage, a suspended chord is not necessarily resolved in this way. Suspended chords may also included the 7th.
Suspended Chords in Jazz
The jazz approach to suspended chords is often a bit different to what was described above. As described by Mark Levine in 'The Jazz Piano Book', jazz musicians will play a major triad one tone below the root of the chord, e.g.
This is a Gsus chord. (Notice no specified 4th or 2nd.) We see in this example a G played by the left hand, and an F triad played by the right hand. Working from the G as the root, this chord has root, 4th, 7th and 9th. Remembering that the 9th is the same note as the 2nd, we see that this chord has no 3rd but the 4th and the 2nd. We could also notate this could as F/G (an F chord over a G bass). Dropping the 4th a semitone resolves the chord into a G7 (with added 9th).
If the 5th is included in the suspended chord, then instead of F/G, we have Dm7/G:
Another difference in the context of jazz is that sometimes the 3rd is included(!):
Jazz musicians do this to create a greater degree of dissonance to add interest to what they are playing.
Fourth Chords
The basic chords we looked at in an earlier post, along with their extensions, were formed by stacking notes in thirds (major or minor). But we can stack notes in fourths instead, and the resulting chords are quite interesting.
The diagram above shows a series of fourth chords, representing the different voicings achieved as we move the formation up a C scale.
The first chord can be recognised as an inversion of a C6/9 chord. Similarly, the fourth chord shown is an F6/9.
The second chord can be recognised as a Dm6/9, but we could also use it as a G13 chord (it lacks only the G from this chord).
The third chord is not so easy to identify, but can be played as a variety of Gsus. The same is true of the sixth chord.
The fifth chord contains all the notes of a G13 chord.
The seventh chord is the oddest sounding. Notewise, it is an F6/9 with an added ♯11. (In the 'Jazz Piano Book', Mark Levine calls this an F∆7♯4, but this is with the understanding that a 6/9 chord can be substituted for a major seventh chord.)
Polychords
A polychord can be defined as a chord over another different chord:
The notation shown above, with the names of the chords stacked vertically, separated by a line, is a common way of notating such structures. The combination of chords in this fashion produces interesting sounds, mainly through dissonance. Polychords are not often seen outside the jazz context.
The same two chords could be named in other ways. For example, the first could be interpreted as a C11 ♭9 ♭13; the second could be understood as a G13♯11.
Where polychords are indicated on a piece of music, the performer may not necessarily include all notes of each chord, allowing for interpretation of how the piece should sound.
Consider the following chords (taken from the piano part of a 1950s jazz standard):
We could notate the chords here (except the last, which is just an inversion of E7) as polychords:
A∆7 over B, A over Gm, D over A, F#m7 over D.
(On the piece in question, the chords are actually marked more simply as A∆9, B♭dim, Bm11, E7sus.)
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