Functional harmony is a set of ideas used to create logical chords progressions where each chord has a definable role. The chords job depends on its relationship to the tonic chord (I). Some Chords will sound stable and resolved, while other chords will sound unresolved and unexpected,

The aim of this tutorial is to give ideas and understanding to constructing chord progressions quicker, easier and with more confidence, although some music theory knowledge is needed. Please check out our music Theory tutorial to get up to speed, Found Here


What is a tonic chord

Its very important to understand the relevance of the tonic chord as the chords only do their intended job in relation to the established tonic chord. A tonic chord is the root of the scale, it feels like the start and the final resolution, its the chord our ears want, and expect, to hear. 

For simplicity I will work with the C major scale

C Major scale (All the white notes)



We use roman numerals to name their relationship with the tonic chord and these relationships can be categorized into resolved (consonance) and unresolved (dissonance).

A mixture of these makes music more exciting and far more interesting.  The unexpected dissonance chords will always want to move back to the tonic to relieve the tension. 

So firstly, what chords are classed as dissonance, and what is classed as consonance?


Dissonance

(ii) and (vi) - Week Dissonance

(IV) - Strong Dissonance

(vii) - Strongest Dissonance

Some chords have more dissonance than others, the 4th (IV) and the 7th (vii) has strongest dissonance. The stronger the dissonance the more desire the listener has for the tonic(I) chord, the home.


Consonance

(I) - Home Base (tonic Chord)

(V) - Harmonizing chord

(iii) - Resolving chord

These chords have a close relationship with the tonic, Much like the dissonant chords, some constant chords sound more resolved than others, these chords are the (I) and the (V) of the scale.


So what can we now do with this information?

Playing a mixture of dissonance and consonance, you are always creating tension and resolving it. If using a week dissonance it works well to play a stronger dissonance to create more tension before resolving with a consonance chord. These aren't hard rules of music, they can be broken and manipulated but following them will ensure little to no errors when jamming or constructing chord progressions.

So far I have discussed the theory and understanding of functional harmony, however I have illustrated a more instructional method of the same principles below. The idea is to follow the arrow, you don't have to move to the note next to the current note you play, but you do have to move to a note that's in the same direction of the arrow.  



Some common chord progressions

(I)  - (iv) - (V) - Resolved, Unresolved, Resolved

You could also look at enhancing the dissonance before resolving, this works well if the first dissonance chord is weaker than the next.

(I) – (vi) – (IV) – (V) - Resolved, Unresolved, Unresolved, Resolved.

(ii) - (IV) - (V)- (I) - Unresolved, Unresolved, Resolved, Resolved.


The following Ian O'Donnell's tutorial explains the basics very well. 




Music Theory for guitar, have created a video using logical chord progressions but including chord substitutions using negative harmony.