Quartal harmony is a system of building chord structures on perfect fourths. It’s been used by classical composers such as Stravinsky, Debussy and Bartók and innumerable jazz musicians like McCoy Tyner, Bill Evans and Chick Corea to name but a few. The reason this harmonic device is so popular is for good reason: chords built on fourths don’t have the same air of predictability as more traditional harmony.

In Western harmony we tend to build chords using intervals of major and minor thirds*. With these intervals we can construct nearly all of the ‘useful’ chords found in close to ninety percent of pop, jazz and classical music.

*Major thirds and minor thirds are four- and three-semitone intervals, respectively.

Broadly speaking there are three types of chord: major, minor and dominant. You could argue there are two if you consider a dominant chord to be a form of major chord but I think their distinction warrants an exception.

N.B There are of course other chords composed of major and minor thirds that I’ve omitted here – diminished and augmented chords – but they often function in place of dominant chords.

Normally, we identify major chords as ‘happy’ and minor as ‘sad’ while dominant chords we think of as unresolved, or in anticipation. This is fallible however, as taking a chord out of the context of a progression defeats the point of analysis and it’s perfectly normal to perceive a major chord as contributing towards a minor feel and vice versa (but that’s another topic).

Our tonal system is built upon a controlled use of consonance and dissonance, sometimes even both within one chord. However there are harmonies that are constructed with other intervals, such as fourths and fifths, and these emit less of an obvious major or minor feeling.

An interval of a fourth is five semitones, and a fifth is seven semitones. Constructing chords based on these intervals can be more harmonically ambiguous and it’s perhaps for this reason that composers use them to illustrate more complex themes.

Here’s bass player and excellent YouTuber Adam Neely explaining a little about quartal harmony in the theme music to his channel. It’s a bit bass-specific and covers some other topics (like auto-tune) but still a good watch:

Let’s have a look at a few of the different ways fourths and fifths can be used in harmony, their different functions and how to effectively use them to spruce up your harmonies.

Suspended Chords

One voicing that many musicians (guitarists especially) might have come across is the suspended third, or ‘sus chord’. To understand what it is, let’s first briefly look at the construction of major and minor chords (for a more in-depth look, have a look at this).

Major and minor chords are constructed in much the same way in that they both contain a root note and perfect fifth interval. So, for example, C major and C minor would contain both a C (root) and a G (perfect fifth) intervals.

In contrast, C major contains an E and C minor contains an Eb. These notes are the respective third note in the C major and C minor scale. This note alone determines the tonality of the chords. Here’s a C major chord followed by a C minor:

Replacing this with one of its surrounding notes can ‘suspend’ the tonality, making it neither major nor minor. There are two options available, a D or an F (the second or fourth note in both C major and minor scales).

These chords are appropriately called sus2 and sus4 chords, and are common place when resolving a chord progression. Here’s a sus2 chord followed by a sus4. In each example I’ve highlighted the suspended note in green:

Let’s take a look at these examples in context. Here’s a simple ii V I progression in C major. Each time we suspend the V chord only to resolve back and then lead to the I. Here’s an example with Gsus4 (again, the suspended note is highlighted in green):

Look at the highest note in each chord: the C note in Gsus4 leads to the B in G and then back up to the C in the C chord in the last bar. Let’s take a look at an example with a Gsus2:

Here the A from the D- stays in the Gsus2 chord which leads up to a B in the G chord and finally the C in the C chord.

Sus chords have been used to great effects by countless rock bands, sometimes when sitting on one chord for a bar or two they’ll flick between the major and sus4 for example. The Who’s Pete Townshend was a proponent of this, as you can see in this Guitar World article.

Maiden Chelsea

Herbie Hancock’s 1965 concept album Maiden Voyage was sandwiched between the Modal Jazz and Hard Bop eras, and arguably has influences of both idioms. The title track employs the sort of suspended harmonies discussed but rather than using them to transition to the tonic in a turn around or ii V I, they form the sonic palette for the melody:

Let’s look at the A section, a simple repeating rhythmic chord pattern moving from D9sus4 to F9sus4. The use of sus chords directs the attention away from an obvious major or minor composition (although a tonal centre of F following a D would imply some mode of D minor):

Here are the chords:

Here’s the melody:

Robert Glasper has done a fantastic version of this blended nicely with Radiohead’s Everything in its Right Place, check it out:

The So What Voicing

Similar to Maiden Voyage is Miles Davis’ So What (from the 1959 album Kind of Blue). So What is less of a melodic composition and more a bed for modal improvisation. In place of a melody is a repeated bass figure and the synonymous ‘so what’ voicings, transposed up and down.

The voicing is played on the piano by Bill Evans. It’s E and A in the left hand with a G second inversion in the right hand (E, A, D, G and B which, interestingly, is the first five open strings on a guitar) which is then repeated a tone down.

I’ve added in some vinyl crackle and the hiss from the original record for some faux authenticity. Here’s the main bass figure and chords, heard during the intro before Miles’s solo:

The piece is a 32-bar cycle with the voicings shifted up a semitone in the third block of eight and back down for the last. I’ve marked the modes for improvisation above the voicings, too:

Ethan Hein has written at length about So What in his blog.

Other Voicings

Similarly to the above example, there are lots of voicings possible using parallel (or stacked) fourths and fifths. McCoy Tyner is king of this sort of harmony. You can experiment by outlining the harmony with your left hand and stacking fourths (or fifths if you can stretch) with your right.

Let’s start off looking at some minor voicings in the key of G minor. Using G-7 shell chords with our left hand, I’ll walk up the G Dorian scale with the right using parallel fourths:

I’ve not even included all of the chromatic voicings between these scale degrees where all sorts of interesting harmonies are to be had. Let’s do the same with G major this time, however using parallel fifths instead of fourths.

Fourths don’t work as well in major keys as they can cause dissonance with the third and seventh degrees, which are key component of this tonality. We’ll ascend in the G Lydian mode this time:

Again, some of these voicings might look a bit awkward or forced, particularly bars 4 and 7. I normally don’t like to mix accidentals within a chord but this makes the most sense to me. I’m opting for #11 rather than b5 as it’s assumed the tonality is that of G Lydian, not some sort of diminished harmony.

Here’s the superb YouTube user Lot2Learn doing his flip on how McCoy Tyner might approach the standard Autumn Leaves:

Footprints

Wayne Shorter’s Footprints from 1966, taken from the album Adam’s Apple, which Herbie Hancock was also on piano duties for:

The composition is based on a 12-bar blues in C minor, and contains one of the most debated turnarounds in the jazz repertoire. Here we can hear the melody is stacked fourths between the trumpet and tenor sax, with the pianist using rich minor 11 voicings over a bass ostinato. I’m not going to attempt to emulate this in Logic (actually I already attempted, and it sounded awful):

Much has been written about the Footprints changes, check this from Peter Spitzer’s blog.

Slash Chords

You might have come across C/E before, or G/D, A-/E etc. These are what are known as ‘slash chords’, and are ordinary voicings with an instruction of what note to play in the bass: so C/E is a simple C chord with an E in the bass. Certain types of slash chord can create some interesting harmonies, functioning in place of the V or IV chord in a typical turn around. They can also add certain colours and flavours to more ordinary sequences.

Sometimes it’s easier to denote chords as a slash chord rather than going into detail about the extension; for example, F∆7/G is (arguably) simpler to voice than G13sus (or whatever you might want to call it). However I’m going to leave these where they are for now, as I’ll be doing a specific article on inversions and slash chords down the line.

Conclusion

Using fourths in your own music isn’t rocket science but it’s useful to understand the basics of how these chords work, their function and tonality – as with everything in music it’s more important to use your ears.

Chords with stacked intervals can sound both cool and hot, ambiguous and sophisticated at the same time: McCoy Tyner used rapid flurries of variously connected pentatonic scales to improvise over these voicings; others have used a modal approach. I’ll leave you with a picture from the recording of Kind of Blue with everyone looking dead introspective: