Modulation

Some initial examples of modulation have already been introduced in exploring [‘Tonicising’ and the circle of fifths], [The chord of the flattened 7th and its potential] and [Modulation]. Conventionally, modulation patterns derived from adding either a flat or a sharp to the prevailing tonality in order to prolong the sense of overall flow, extending the proportions and local colour in music from the Renaissance onwards. The Baroque period saw sequences of modulation introduced around the circle-of fifths; and the Romantic period saw the introduction of expressive excursions to more distant keys. In line with this potted reduction of musical history, we will deal with the potential of modulation in a similar ordering.

We should already have visited and responded to [Dominant sevenths] and considered the manner in which the 7th is present in the harmonic series and therefore lends itself directly to achieving modulation to the subdominant:

I→I7→tonicising sign→‘old’ IV has now become I.

This represents movement ‘flatwards’ around the clock face of the circle of fifths (see [‘Tonicising’ and the circle of fifths]). The next option we should visit is modulating ‘sharpwards’, which will involve bringing the ‘old’ dominant into the tonic position. Compared to moving to the subdominant, this is a more radical and complex procedure, whatever the textbooks tell us regarding its key role in the development of musical proportion and style. It requires an additional step; and the introduction of a new gesture ‘outside’ the initial framework of the Primary Triads. This gives access to chord II, the supertonic Major, and involves the left arm moving outside the body horizontally to the left with the hand making the thumbs-up gesture familiar from the hand-sign for the sharpened 4th degree of the scale, fi. The progressions can then be notated to represent these respective gestures:

I→II→II7→tonicising sign→‘old’ V has now become I.

Each of the procedures can now be repeated in order to move either flatwards or sharpwards around the circle-of-fifths.

We can next consider some modulatory procedures that employ these same techniques to elaborate tonal excursions further. Initial potential for this is dealt with here: more wide-ranging possibilities that arose during the Romantic period are outlined in [Short cuts to alternative modulatory pathways].

To begin with, we should revise the employment of what we have already dealt with in order to illustrate how we can return to the original tonic having departed from it. Here are two progressions, one modulating to the subdominant before returning to the tonic, the other visiting the dominant and then returning:

I→I7→tonicising sign→‘old’ IV has now become I→→II→II7→‘old’ I returns

I→II→II7→‘old’ V has now become I→→I7→‘old’ I returns.

It is, of course, perfectly possible – sometimes even preferable – to move directly from chord I to chord II7. Indeed, where this is intended, the voice-leading required permits the additional potential of sustaining note 1 as the unchanged link between the two chords:

Chords I→II7→V= new I

Voice 1 5→6→5

Voice 2 5→4#→5

Voice 3 3→2→2

Voice 4 1→1→7