The Basis of Harmony

Diatonic harmony within music refers to a collection of chords that are built upon a key centre’s scale. Although the evolution of Western harmony has gradually become more intricate, the basis of harmony has remained unchanged and can be reduced down to three fundamental chords: I, IV, & V.

Labelling Chords As Roman Numerals

Chords are labelled using a roman numeral number system, this makes a more efficient system that allows transposing to different keys.

I, IV & V Chords In Music

The I, IV and V chords are the staple chords in music and are major in tonality within Major Scale Harmony.

Major vs Minor Harmony

Harmony depends on the context of the scale it is derived from eg:

• Major harmony refers to chords built from a major type scale.
• Minor harmony refers to chords built from a minor type scale.

Chord progression written out in roman numerals

. .

I

IV

V

I

. .

In the key of C Major this translates to

. .

C

F

G

C

. .

Tips to help you identify a song's key

Becoming familiar with the I, IV, & V major chords will help you quickly identify the key of songs in Major keys.

• Look out for the two major chords a tone apart which equates to the IV & V chords. This leaves the I chord to be the key’s identifier

Harmonic Context

In harmonic context, each chord has a particular quality which can be described using terms like tension and release.

I: Tonic

The I chord is the home chord within a key, the stabilizer.

IV: Sub-Dominant

The IV has a hybrid quality of both the I & V chords. It can act as stabilizer or can be heard as a tension chord wanting to resove to its’ I chord.

V: Dominant

The V chord holds an inherant tension and acts as chord that wants to resolve to its’ I chord. The V - I movement creates the strongest resolution in music.

Try it out

Major 12 Bar Blues Progression

𝄞

I

IV

I

IV

I

V

IV

I

V

. .