Day Nine: Modulation

Key relations are among the most powerful means of expression in music.

This post is part of 14 Days of Harmony, a free course for musicians who want to deepen their understanding of harmony, and learn how to develop their connection with sound as a result. You can view the entire course here.

We've spoken a lot about stability in music: how the ear hears stability in a single musical tone; how one tone can be more stable than another even if it's heard later in time; how chords can be organized by scales with degree-relations that contribute to or take away from the stability of the tonic; how cadences can establish a stable chord or interval through the use of dissonances and resolving harmonic tension. 

But frankly, stability 

can be so 

... boring. 

Modulation is the art of harmonic mutiny!

It is the artful challenge of the stability of the tonic, eventually allowing the victory of a new tone to emerge as the stable tone!! It is about leaving the key and moving on a clear path from one stable tonal center to another. At its core, a modulation is the transference of stability from one sound into a different one. 

Variety is the spice of life, and in tonal music we find the same principle at work. A modulation is a musical revolution. Recall the experience that musical tension itself is felt from contrast, the concrete juxtaposition of two sounds. We hear how they are different, and how they are the same. If life is to emerge from a work of art, then we have to engage in this conflict that is made possible by the emergence of musical tension.

In this lesson we are pivoting toward learning how to destabilize a tone and move away from it to somewhere else. This struggle is central to tonality, the system of musical organization in the West based on relative stability and key relations. Renaissance musicians in the 16th and 17th century composed using a different system that we call modal that relied more on scales and intervalic relations. Our tonal system was codified by Johann Sebastian Bach (1685-1750) whose music expressed all that was harmonically and contrapuntally possible with the 12 major and minor keys. Eventually, composers would find ways to express new key relations, and establish one of the most powerful means of human expression in music. 

Tonality took centuries to develop. After Bach, tonal music has been enormously expanded upon by Haydn, Beethoven, Brahms, Bruckner, and so many others who have used tonality to build bigger musical forms. After decades of development, the fundamentals themselves were eventually treated not as the most stable note but as a leading tone, yielding to newer forms of expression through use of chromatic harmony. Eventually history would birth composers who have treated the 12 tones in a very different way. These are the composers of the Second Viennese School. Despite having modulated vastly their tonal origins, their dodecaphonic works clearly show a highly thought out musical means that are similar to the techniques of harmonic and contrapuntal expression in music by J. S. Bach. And in our contemporary understanding, these relations all have their roots in the relations that the tones have among themselves, organized by the structures of Nature and appreciated by the human body. 

The Tonal System: What defines a stable tonality?

A tonic chord is defined by its dominant (the chord built on top of the upper fifth of the tonic) and its subdominant (the chord built on top of the lower fifth of the tonic). Tonality as a system is a way of thinking about the musical tones as major and minor chords, and these chords each have their respective scales and keys, determined by the accidentals that are in the descending scale. The richness of the harmonic universe could be freely understood by the following. Each of the 12 tones has a chord (commonly either major or minor) and a key associated with it. So the key relations themselves can be understood and experienced by the intervallic relation between the two tonics.

Oversimplified: Tones = Chords = Keys

What defines a stable tonality?

The stable tonic is defined and strengthened by its dominant (upper fifth) and subdominant (lower fifth). Essentially, a cadence is the expression of a tonality.

Figure 1. The reign of the tonic as the 'central' tonality is established by cadence harmonies. Because the system of tonality allows all of the 12 tones with their own respective major and minor keys, any of the 12 tones can be established as stable provided we hear its upper and lower fifth functioning as dominant and subdominant harmony.

Part of the goal and charm of a modulation comes from how the transferral of those subdominant and dominant qualities are given to notes outside of the original key. To understand how to easily do that, it's best to develop a deep appreciation for fifth relations.