Many successful songs are derived from simple, catchy chord sequences. However, there are a wealth of interesting chords and extensions that can make a song stand out more than the rest, by avoiding musical clichés and not merely ‘recycling’ the same three chords again and again.
A few of these are easy to write with, and they can even be added to a song after it is written without having to change the whole structure.
The Suspended Chord (sus)
Suspended chords are common in all music, and are created by moving the third up a semitone, into a fourth. In a C Major chord, this means the notes would be C, F, and G instead of C, E, and G; a simple substitution.
The effect a suspended chord has is to suggest that something is unresolved, meaning you can then resolve it by returning to the third, or even by moving to a different key. These chords are more successful at the beginning or end of a song if placed where the listener is expecting a simple major chord. An example of this would be in The Who’s Pinball Wizard, where the verses feature suspended chords that are resolved by returning to the third in every other bar. Sometimes a succession of different suspended chords can create a pleasant effect, but don’t try and make an entire song out of them!
The Minor Seventh Chord (m7)
Many funk and disco songs are full of minor sevenths, but they can be used to great effect in an ordinary rock or pop song. If you have a minor chord or a sequence of minor chords, try adding the seventh note in a chord’s scale onto the end of it. For example, E Minor contains the notes E, G, and B, while E Minor Seventh contains E, G, B, and D.
The extra note has a thickening effect that can be valuable in certain contexts, though don’t overdo it. It’s best to try it out with an existing song, and listen to what the seventh is doing to your harmony. It can make a progression of chords seem groovier but sacrifices the sad, dark qualities of the original minor chord. The chorus from The Bee Gees’ Night Fever is built entirely from minor seventh chords.
The Major Seventh Chord (M7)
This chord is beautiful and surprisingly underused in favorite music. As with the minor seventh, an extra note is added, but this time it is the unflattened seventh note in the scale (the one just before the tonic itself), and it is more commonly added to a major chord. In C Major, this would make a chord with the notes C, E, G, and B.
An ordinary C7 chord would contain Bb, but the B natural adds a dreamy quality to the sound instead. As with the minor sevenths, major sevenths work well in groups so that you could make an entire chord sequence out of them for a thick, gorgeous sounds, such as in the main vamp to Elton John’s Bennie and the Jets. Experiment with them and see for yourself where they fit and where they don’t. A hard rock song rarely has a place for the major seventh chord!
The Diminished/Augmented Chord (dim/aug)
These are two separate chords, but they have a similar effect on harmony. The diminished chord replaces the usual third and fifth with their flattened equivalents (so F, A, C becomes F, Ab, Cb/B) while the augmented chord sharpens only the fifth (so F, A, C becomes F, A, C#). If you’re not used to these chords, they can seem ugly, and they are on their own.
Bear in mind that diminished and augmented chords work best as part of a sequence, where the melody “passes through” them to arrive somewhere else. The diminished chord has a sinister effect but adds a lot of colors when used to move into a new key. The augmented chord has a similar impact on the suspended chord, raising the tension before everything is resolved. Both have a significant role in David Bowie’s Life on Mars, where they are used to ascend or descend between other chords in the song’s chorus.
The Ninth, Eleventh and Thirteenth Chords (9, 11, 13)
Finally, we have three more extension chords that go beyond the seventh. Common in jazz, these chords are intended to create dense, intricate harmonies. They are formed merely by adding the note of the scale relevant to each number, so in the key of C, a C Ninth chord would include C, E, G, Bb and D (the seventh is optional but is usually retained). The eleventh adds another note to make C, E, G, Bb, D and F (again, the previous extensions are optional but help establish the direction the harmony is going in). The biggest of them all, the thirteenth of C would consist of C, E, G, Bb, D, F, A!
These chords get increasingly harder to use as they go up in number, but when applied expertly they can make even the dullest of songs seem exciting and varied. A particular example of these extended chords in action would be the introduction to Dave Brubeck’s Strange Meadow Lark, which uses all three in conjunction with various other complex chords. They do not have to be restrained to jazz alone though.