Understanding Chord Progressions: Intervals, Leading Notes & Tension

In our blog covering chord theory, we looked at how chords are built, and here, we’ll see what happens when you place one chord after another to build a chord progression and why some combinations work better than others. We’ll talk about intervals, how to build tension, what leading notes do, resolutions and sus-chords. There will be a bit of studying involved, but in the end, it’ll only speed up your writing process.

Introduction
Intervals
Building Tension & Resolving It
Leading Notes
On the Way
Hearing the Intervals
Sus Chords
The Minor Keys
Harmonic Minor
Tritones
Minor Keys & Chords
The Common Keys
See Also…

Introduction

To understand the theory included in this blog, it’s a good idea to start by reading these articles as well:

Intervals

Being able to think about notes in terms of intervals can come in really handy. For example, if you’re writing a piece in the key of G, then G is your first interval, A is the second interval, B is the third, and this goes all the way up to F♯ (the seventh interval). The intervals are notated by Roman numerals, and the first interval is generally referred to as the tonic (the following intervals also have special names, but we don’t need to go into those here).

You can also notate chord progressions in intervals. When writing out a progression in A, where we’re using chords A, D, and E, you can notate the progression by just writing I-IV-V. If the song is in G, and you’re using chords G, Em, Am, and D, then you can write out the progression as I-VI-II-V. In many songs, the chords will alternate in a repeating pattern, the most common being a I-IV, I-V or I-IV-V7 patterned progression. Sevenths also pop up a lot in blues music, so you can even get runs like I7-IV7-V7, or II-V-I. The II-V pattern is often used in jazz – by missing out the last ‘I’, the tension of the piece is stretched out (hopefully, by the end of this blog, you’ll understand why).

Try thinking about songs and chord progressions not just in terms of the chords, but also intervals. Master the art and you’ll notice that your writing gets faster, and transposing songs into a different key immediately becomes a lot easier.

Below, you can see (per major key) which chord belongs to which interval. Click on the image to enlarge it.

Building Tension & Resolving It

From understanding intervals, we move onto how to build suspension in chord progressions before resolving it. Various elements of the music will have a part to play in its tension – the volume and intensity immediately spring to mind. But largely, it’s the note combination that lays down the building blocks that create the arc of tension. Take the melody: the first note of the melody is usually the root note or one of the other notes of the first chord. The melody will often wander away from the first note, meandering through other notes before finally returning home to the root. While this can definitely have a kind of narrative that builds tension before resolving it, some of the essential ‘storytelling’ happens in the chords.

If you’re playing a song in D, then it’s likely that your opening chord will be D major. Even just moving to another chord from D-major will build some tension because it’s as if the music always wants to ‘return home’ to that D chord. By starting with a D, then wandering across a couple of other chords, the tension is created, and by returning back to the D, the tension is resolved. For some magic reason, the urge to return back to the opening chord is strongest when you reach the fifth interval (V), and in the key of D, that’s an A major chord. This urge gets even stronger when you add a seventh to the A chord to get an A7 (V7).

Leading Notes

So, why is it that the V (fifth interval) or V7 (seventh) chord creates such a strong musical urge to return to the opening chord (I)? In the first place, the ‘V’ chord (together with the IV chord) is the furthest away you can get from the ‘I’ chord. The distance between intervals is important when it comes to creating tension, which is why the ‘V’ chord wins out (and the V7 chord rules them all) when compared to the IV chord, and this is because of the leading notes. Leading notes are the notes in a chord that sit a semitone away from the notes that make up the opening chord – the chord where the music has an urge towards; where it can naturally resolve.

Take a song in C. The opening chord, or ‘home’ chord is likely to be C-major, kicking off a C, E, and G chord progression. The fifth interval in the progression is the G-major chord, which has a B as the leading note. This special B sits just a tantalising semitone away from C, so will always be drawn back there. In the key of C, you can also turn the G chord into a seventh, so G7 (G, B, D, F), which adds a second leading note: an F, which, since it lies just a semitone away, naturally wants to resolve into the E of the C-major chord. Seventh chords also have an extra dose of tension to them since the seventh note rubs up against the root note of the chord. In the G7 chord, the F rubs up against the G – and this ‘rubbing’ is more generally referred to as dissonance (which we’ll talk about in more detail later when we cover tritones).

On The Way

In the F-major chord (the fourth interval of our C-major chord progression), there’s only one leading note: the F, which naturally wants to resolve into an E. Also, one of the notes of the F-major chord is already home, since the fifth in the F-major chord is a C – the root note of the C-major chord. And, if we really get into it, we find that the G7 chord (V7) also has a note in common with the C-major ‘home’ chord (I). The root note (the G) of the G7 is the fifth of the C-major chord, and will always want to come back to the tonic (the root note). This still works as a kind of leading note, even though the notes don’t sit a semitone apart.

A tonic coupled with another bass note from the chord, a C/G for example (a C-chord with a G as the bass) doesn’t quite sound fully ‘at home’, but is kind of ‘on the way home’. Try playing a G7 then a C-major – that definitely feels like coming home. Like stories, music is made up of building tension before resolving it and returning home, and like stories, you can stretch and suspend that tension out for as long as you want. This stretching suspense is something that happens a lot in jazz where the chord progressions are often constructed in such a way that it feels like the ‘home’ chord is just about to hit, then it doesn’t.

Hearing the Intervals

So, you might be thinking, “how can I just quickly find the right chords and spit out songs faster? Why do I need to know about leading notes, tension, and resolution?” The answer is actually pretty obvious: if you understand all of this stuff then it’ll get much easier and quicker to find the next chord and build a progression that works. Sure, it’s also worth training your ear so you can hear the different intervals straight away and so you can notice exactly when the V7 wants to resolve into the I, or that the piece is resolved by taking a route through the IV structure. And, if you hear a minor chord played in a song that’s in a major key, then it’s likely that it’s a second, third, or sixth interval chord. The fact is that, with this knowledge on your side, you’ll actually be able to understand what you hear and be able to seek out the perfect set of chords in no time.

Sus Chords

Sticking with the idea that there are chords that lead to a natural resolution, besides the chords that we’ve already talked about, there are also sus-chords. These are still scale-specific chords, where ‘sus’ stands for suspended, which in the context of chord theory, refers to the diminished third. So, with a sus4 chord, the third is replaced by the fourth (the fourth note in the scale). The Csus2 chord is made up of C, D, and G, and the Csus4 chord is made up of C, F, and G. The suspended, or ‘delayed’ third can then follow the chord, but it’s not necessary, since there really are no rules when it comes to resolving the tension of a chord progression. The beauty of sus chords is they literally ‘suspend’ the tension before the resolution and they can resolve into minor chords just as naturally as they resolve into major chords. As such, they’re used across a wide range of genres. Quite a few sus chords pop up in You Gotta Move by Gino Vanelli and Cold as Ice by Foreigner. Ballads will often feature a sus chord, but when it comes to harder forms of rock, they’re less common since rock is usually built on power chords (which only include the root note and the fifth). A gorgeous example of of a sus4 and sus2 (and one that should be familiar to everyone) comes from a church organ song: two counts of Csus4 (G, C, F), one count of C (G, C, E), one count of Csus2 (G, C, D), and four counts of C (G, C, E).

The Minor Keys

Now we’ll take a look at the minor keys. Every one of the major keys has a parallel minor key that lies a diminished third lower. The parallel minor key of C-major is A-minor, and in principle, it uses the same notes as the C-major key, but played from A to A. This is also known as the aeolian minor scale, the ‘original minor’, or the ‘diminished third scale’. Within this key, we hear the same chords as we would in C-major, but here the ‘home’ chord is A-minor.

Harmonic Minor

In reality, the minor key is often used to make small adjustments. By raising the seventh note of the original minor scale by a semitone, a harmonic minor is created. For example, take the A-minor scale (the parallel of the C-major), which runs as follows: A, B, C, D, E, F, G, A. The harmonic minor then becomes: A, B, C, D, E, F, G♯, A. This scale has a more familiar sound to the ears. And the point of raising that G to a G♯? Well, this is where the leading note comes in again. Since the G♯ sits a semitone away from the root note (A), it’s the leading note towards A. So, by shifting the G up to to a G♯, a leading note is added to the chord on the fifth interval. In A-minor, that’s the E-chord, and sticking to the aeolian scale, that’s an E-minor chord (E, G, B). If you were to turn it into a harmonic minor, then the chord would become E-major (E, G♯, B), giving us our G♯ leading note, which will want to resolve naturally into the home chord – A-minor (A, C, E). Of course, we can intensify the urge to return home by turning the chord into a seventh, so E7 (E, G♯, B, D), where the E and D provide that all-important dissonance.

Tritones

While the E and D create dissonance, the G♯ against the D makes things even more intense. This is because the G♯ and D lie three whole notes apart, which is what’s referred to as a tritone. If you play an E and the next D up on a piano, the E will want to resolve to an A and the D will want to go to a C (in the minor key). If you play a G♯ and the next D up, the G♯ will want to head to the A and the D will want to head to the C.

While the leading note in major keys is strong because of the semitone distance (so the D in the E7 chord is desperate to resolve into the C♯ of the A-major chord), you could say that the tritone has an even stronger urge to resolve. Many songs written in minor keys are largely in original minor and use the harmonic minor as a kind of ‘tension booster’. Only when it hits that fifth interval is the harmonic minor used to bring the tension to a hair-raising climax before it resolves. As soon as you get familiar with the phenomenon, you’ll be able to recognise it in any song or piece.

Minor Keys & Chords

Since A-minor is the parallel of C-major, we’ll start with an overview of A-minor. A little note: the minor key is always parallel to its third interval (so A-minor is parallel to C-major, B-minor is parallel to D-major and so on). Click on the image to enlarge it.

The Most Common Keys

While there are only twelve different keys in Western music (C to B), that’s really more than enough to play with. In reality, there are some keys that are actually more popular than others – so are more commonly used. This is definitely something worth knowing when writing music. For example, countless guitar-based songs are written in D, A or E, and C. Why? Because the chords included in these keys are all open chords, and are played at the bottom of the neck, which is naturally more comfortable. Open chords also have a more lush and full sound to them. Brass band pieces are often written in F, B♯, Eb, and C. Why? Because many of the core brass instruments (like the tenor saxophone and trumpet) are Bb instruments, so are tuned a note below the notation they play. This is why notation for this kind of brass instrument is written a whole note higher than that which is actually heard. Many wind instrument standards are written in F, Bb, Eb, or C, where the corresponding notation becomes G, C, F, or D, respectively. These keys are also more pleasant to read for a wind musician, since they don’t have so many sharps and flats. Alto saxophones and baritone saxophones are in Eb, so play with three sharps less (or three flats more) than instruments in C (like a guitar, bass, or piano). Songs written for female singers often sit around the C, D, or E keys, while songs written for male singers are usually in F, G, or A. Of course, this depends on the vocal range of each individual singer.