21 The Forces of Tonal Harmony

Triads are the basic sonic entities in tonal harmony. They constitute the unifying sound source that cannot be broken down into smaller constituent elements. However, independently, they have no emotional force. Harmony is the organization of the succession of triads in order to develop emotional force.

There are three categories of triads:

The Tonic [I]; a sonority wherein there is no tension.

a. The Pre-dominants: Supertonic [ii], Mediant [iii], Sub-dominant [IV], and Sub-mediant [vi]; wherein tension is building between the Tonic and ultimately leading to the Dominant.

b. The Terminal Pre-dominants: Augmented 6th Chords [It 6, Ger 6, Fr 6, Sw 6], the Neapolitan 6 th [N6], and the Cadential 6/4; sonorities which are used as insertions between Pre-dominants and the Dominant. Their function is to delay the arrival of the Dominant but also tend to resolve to it rather than returning to the Pre-dominant area. The so-called I 6/4 chord cannot be labeled as such because this notion implies that it is a derivation of the Tonic, and therefore must exhibit no tension. However it is a function of the impending Dominant and therefore creates great tension.

The Dominant [V] and Dominant Functions [V7, V9, viio]; sonorities wherein tension is at its peak and resolution to the tonic (in the form of a cadence) is strongest. The triad built on the seventh scale degree of a major key (the so-called viio) does not function as an independent sonority, rather it is simply the V7 chord without the root and functions exactly the same [to identify these sonorities as being of a different nature would be similar to make the conclusion that a green chair and a blue chair need be distinguished primarily by color rather than as something on which to sit]. Any dominant chord which adds sonorities beyond V9 (V11, V13, etc.) create a situation wherein the resolution notes sound with the tension notes and therefore do not function as part of the Dominant.

The three forces produced by these categories of triads, namely 1. no tension, 2. increasing tension, and 3. greatest tension, constitute the whole of harmonic composition; the order of the triads give rise to emotional force. It is in the Pre-dominant region that the most substantial portion of the emotional development takes place. The use of deceptive motion, resolving the Dominant to the Sub-mediant rather than to the Tonic, returns the progression back to the region of Pre-dominants and thus tension can be further put into motion.

Thus it can be said that triadic harmony, which is based on a succession of the most basic of sonorities, contains progressive tension, or tension that is created only over time. However, if one isolates a ‘still-life’ fragment within the progression, no tension can be perceived; the forces that encourage the sonorities into further succession is not present. Temporal tension, or tension that is produced within the transitory sound of a sonority or between one triad and the next. This is accomplished by the use of Non-harmonic tones, or pitches not a natural part of the triad that are nonetheless sounded alongside the triads.

Non-harmonic tones are the result of voice leading dissonances, wherein individual pitches that constitute triads are made to connect with pitches of the succeeding triads via notes other than common tones between the two. Similarly, there exist passing chords, or triads that do not serve a functional role, but are employed in the same manner as non-harmonic tones.

The emotional tension that results from the use of non-harmonic tones (and their subsequent resolution) in congruence with the placement of triads in a succession that results in a force to propel harmonic progression, is the whole of tonal composition. Motives, sequence, imitation, form, and other concepts are parts of compositional constructs that are not necessarily part of the tonal model exclusively. Instead, these form the basis of the intellectual development of a composition.

SUMMATION CHART

Chromaticism and triadic expansion are the fundamental means for extending the material resources within the tonal hierarchy. These constructs within a diatonic region can function not only to enlarge the sonic palette, but to allow the composer a means to focus the control of the forces of tonal harmony to a very fine degree. The aforementioned inclusion of the chromatic sonorities of the Augmented 6th family and the Neapolitan 6th into the body of naturally occurring sonorities are essentially stylized chromatic alterations. Chromaticism within tonal harmony can be classified into three categories:

The alteration of triads or non-harmonic tones in order to change the sonority but maintain their inherent function. This is evident primarily in the adjustment of the Dominant in the minor mode to sound equivalent to the Dominant in the major mode. It is also evident in modal mixtures, or the borrowing of one or more sonorities from a parallel key.

The enhancement of sonorities within the diatonic hierarchy by adding tones to a triad that are not part of the diatonic scale. This is, in effect, a shading of the tonal forces.

To aid in the introduction of a tonic other than the established tonic in the piece. This leads foremost to a modulation or a tonicization.

Triadic expansion is essentially the enhancement of a sonority through the addition of tones to a triad that are naturally part of the diatonic scale. This is manifested primarily through the addition of thirds beyond the fifth within the triad construct.

Modulations and/or tonicizations do not constitute a function of tonal harmony in that it creates a dialectic, or argumentative situation between the tonic and another, temporary, tonic (regardless of whether the temporary tonic is diatonically related or otherwise). It creates a context in which other diatonic progressions can be perceived, and therefore must be grouped with the other intellectual compositional constructs.