Writing a bass line for a given soprano

1. Determine cadences. 2. Determine if a predominant is involved with the cadence. 3. Plot unequivocal tonic function throughout the phrase. 4. Devise ways to prolong tonic function throughout the phrase.

a. Prolonging, rather than sitting on, the tonic chord provides tension and release, which helps to create a flow within the phrase.

5. Prolong predominant and dominant, if necessary.

Voice leading for the bass line

1. Make the bass line as melodic as possible. 2. The bass line may have more leaps than a typical soprano line, while maintaining an interesting

contour. 3. Inversions:

a. Root position chords provide stability to the sound. b. First inversion chords allow the bass line to be more melodic. c. Second inversion chords should be one of:

i. Passing six-four ii. Auxiliary (neighbor/pedal) six-four

iii. Cadential six-four d. Third inversion seventh chords contribute to the melodic nature of the bass line and

provide tension that is released in the following first-inversion chord (e.g., V42 – I6 ).

4. Rhythmically and melodically, the bass line should be both independent and interesting. a. Use a variety of motion between soprano and bass

i. Static (repeated notes; use sparingly) ii. Parallel motion (no more than four consecutive; provides unity, not

independence, between the lines) iii. Similar motion (provides moderate independence) iv. Contrasting (provides the greatest independence between the lines) v. Oblique (more independence than parallel/similar motion but less than

contrasting)

Writing in three parts

1. The horizontal voice leading is the most important consideration. 2. Use complete triads whenever possible.

a. If a complete triad is not possible, try to use two roots and a third. 3. Seventh chords

a. Three different pitches should be used. b. The root should be present.

4. All three voices should be as independent as possible. a. Avoid too many consecutive thirds between the soprano and alto.

Writing in four parts

1. The horizontal voice leading is the most important consideration. 2. Root position triads

a. Use two roots, a third, and a fifth, unless the horizontal voice leading requires a different voicing.

i. In the progression from V-vi, it is possible for the vi chord to have a doubled third, due to the resolution of the leading tone.

ii. In a minor key the doubled third is required to avoid an augmented second. b. When root position chords a second apart appear in succession, the three upper voices

must move contrary to the bass in order to avoid parallel fifths and/or octaves. i. An exception to this is the V-vi progression mentioned above.

c. The seventh of a non-dominant seventh chord should be approached by common tone. 3. First inversion triads

a. If the triad is diminished, double the third (bass), else, If the note in the bass is a primary scale degree (1, 4, 5), double the third (bass), else, Double a note other than the third (bass).

4. Second inversion triads a. When voicing a triad in second inversion, always double the fifth (bass).

5. Seventh chords. a. The best voicing includes all four pitches. b. The fifth may be omitted to avoid a voice leading error. In this situation, double the

root. c. Seventh chords of any type may appear in any inversion.

6. The four voices should be as independent as possible. 7. Spacing between adjacent upper voices (soprano/alto; alto/tenor) must not be more than an

octave. a. It is possible to have more than an octave between tenor and bass; normally, we do not

exceed a twelfth.

38 – The Mediant Triad

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38 The Mediant Triad

The Mediant Triad: A Conundrum Thus far in this text, harmonic progression has always been discussed in terms of function. This chapter will deviate from that paradigm because the mediant triad does not fit neatly into any of the predominant, dominant, and tonic functions. Its appearance generally results from melodic motion rather than harmonic progression.

The mediant triad’s uniqueness arises in part from its inclusion of two pitches from the tonic triad ( 3̂, 5̂ ) and two pitches from the dominant triad ( 5̂, 7̂ ). It does not function, however, as either tonic or dominant. Although it includes 7̂, this pitch does not function as a leading tone because of the stability inherent in the perfect fifth created between 3̂ (the root of the chord) and 7̂ (the fifth of the chord). We mentioned earlier that dominant function chords set up an expectation for tonic (see page 7). This expectation is created in part by the inclusion of the leading tone in the V and viio chords. In those chords, however, the leading tone is part of a tritone (in the V7 and viio chords), which creates the expectation for something to follow. Even in the simple V chord, the leading tone is part of a major third, which is not as stable as the perfect fifth or octave.

There are two ways in which the mediant triad can be used. First, it can precede the submediant triad as part of the circle of fifths progression: iii – vi – ii – V – I (see Figure 38-1). Note that, in the minor key, the III chord is major (using the subtonic rather than the leading tone). This creates a “true” dominant relationship between it and the VI chord.

Figure 38-1. The mediant triad in the circle of fifths progression.

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Second, the mediant triad can be used to harmonize 7̂ in the melodic progression 1̂ - 7̂ - 6̂ - 5̂. This is an example of the appearance of the mediant triad resulting from melodic motion. The mediant triad in this situation can be followed by either vi or IV (see Figure 38-2).

Figure 38-2. The mediant triad as a result of melodic motion.

The Mediant Triad in Tonal Practice The mediant triad is not a common chord in tonal music. Apart from the situations described in this chapter, its occurrence is rare. It is found more often in minor keys rather than major keys because it is the relative major of the minor key.