The interaction of chords and melodies centers on one basic point: chord tones or passing (nonharmonic) tones. In FIGURE 11.2, each note of the major scale harmonized with its own chord. Since each melody note was found in each chord that supported it, only chord tones were used. FIGURE 11.3, “Amazing Grace,” used more than just chord tones in the harmonization; it used passing tones as well. Now revisit that example and see what's really going on.

FIGURE 11.4 Chord and Nonchord Tones in “Amazing Grace”

In the example in FIGURE 11.4, the chord tones are highlighted and the passing or nonchord tones are printed normally. Compare the harmony to the melody, and you will see many different points of similarity. In general, for a harmony to work for any given melody, the majority of the melodic tones should be contained in the chord that supports it. There is no steadfast rule of how many tones per bar, but for music to sound consonant, the melody needs to line up with the harmony enough times to make the listener feel as if they're in the same key. A passing tone does not necessarily have to move by step to and from a chord tone, but if you think of the odds, a triad has three notes and a scale has seven, you're most likely using a passing tone as the triad takes three-sevenths of the scale with it and leaves three of the other four tones as passing tones. Only one tone will exist as a true non-harmonic tone, but then again, it may sound just fine.

Key Control

One of the nice things about melodic harmonization is your ability to set up the keys you'd like to use. When looking at a single-note melody, it's almost impossible to tell whether you're in a major or a minor key unless you have some harmony to support it. When you start with just a melody, you can control the mood of the piece by choosing either the major or the related minor key. Since any melodic tone can be taken by at least three different chords, you can control your keys very closely.

Here is a simple example, using a key signature of no sharps and no flats, which could be either C major or A minor. The example uses a whole-note melody over a few bars. Look at the melody by itself in FIGURE 11.5.

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FIGURE 11.5 Basic Melody

Although a melody could apply to either key that the key signature supports, there is one thing that could sway it to the minor key. Remember the leading tone? In the key of A minor, the G is a telltale sign that the piece is in the key of A minor. The melody stayed away from that—completely on purpose—as that would have locked the music into that key.

Getting back to the example, since the G was avoided, look at FIGURE 11.6 to see how this could become a C major melody.

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FIGURE 11.6 Basic Melody Harmonized in C

Simply by choosing chords from the key of C, making sure to throw the all-important dominant V chord in, establishes the key of C major. There might have been a chord ladder used, but it was more of a process of elimination at a piano or guitar to see what chords fit best with the notes written.

Now, to push the piece in the direction of A minor, just use chords from the key of A minor and make sure that it has its own dominant V chord—in this case, E7. FIGURE 11.7 shows the result.

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FIGURE 11.7 Same Basic Melody Harmonized in A Minor

By sticking to A minor chords and typical progressions in that key, it is pretty easy to transform this basic melody into an A minor melody. It's amazing that a simple melody has to be defined by its chords, but this is the general balance that must be followed: Melodies and harmonies rely on each other. Neither one can exist solely on its own.