Relating melody to chords
In general, harmonic accompaniments are based on the principle that the pitch of a melody note belongs to one of the pitch classes in the chord that accompanies it. For instance, if the melody note is E, the accompanying chord will most likely contain an E as well. For brevity, we’ll refer to a chord’s constituent pitch classes as its “chord tones.”
When a melody note is a chord tone, it creates a “consonant” or “harmonious” relationship between melody and accompaniment. However, it often happens that a melody note is not a chord tone. For instance, if the melody moves scale-wise while the chord doesn’t change, there will be “passing notes” heard briefly between one chord tone and another (since chord tones are normally two scale-steps apart; see Chords: the basics). On the other hand, if the melody sustains a pitch while the chord changes, what was at first a chord tone may not be a chord tone of the new chord, creating what is called a “suspension” or “suspended dissonance.” We will use the word “dissonance” to describe any melody note that is not a chord tone of the chord that accompanies it.
The effect of a dissonance is usually one of discord or tension between melody and accompaniment, often creating a feeling that the melody should move to a chord tone before the chord changes. Dissonance doesn’t mean that the music sounds bad or unpleasant. Most harmonic music uses some combination of consonance and dissonance, and the contrast and balance between them, to create its effects.
If we want to capture how music does this in our notation, we need a way of showing what the chord tones are and when the melody note is and is not a chord tone. A starting point for this might be the way we notated a melody with drone. In effect, a drone could be considered as a chord that doesn’t change throughout an entire piece. By writing the melody and drones in the same space with different thicknesses of line, we were able to see where the melodic pitch does and does not coincide with the drones.
To do the same for changing chords, we could replace part of a pitch line with a thicker or colored line wherever the pitch in question is a chord tone. But remembering that some chords contain extra-scalar pitches, we may want to distinguish those chord tones which are scale degrees from those which are not. Also, since any combination of (for instance) scale degrees 2, 4, and 6 forms a ii chord, the chord tones may not all be actually sounding in every octave, so it might be misleading to notate them in the same way as audible sounds (e.g. with color). On the other hand, we do want to mark the chord tones in the octave(s) where the melody lies, whether they are sounding in that register or not, so that we can easily relate each melody note to the chord tones that are nearest to it in pitch.
It’s clear that most of the horizontal red lines (especially the longer ones) have a continuous black line running through them, which shows that most of the melody notes are chord tones, in other words the melody is largely consonant with the accompaniment. However, occasionally the black line running through the red one is dotted, which indicates a dissonance. The first bar doesn’t count, as the harmonic accompaniment hasn’t started yet, but at the end of bars 3 and 5 we can see “passing notes” where the melody is moving scale-wise between chord tones. In the second system, at the moment where the IV chord begins, there is a brief “suspended dissonance”: the highest pitch, which was a chord tone of the I chord, is held over while the chord changes, becoming a dissonance which is then “resolved” by moving down to the nearest chord tone below it.
At the beginning of the second system, there is another dissonance, this time not prepared by being first presented as a chord tone. This seems to create more tension; perhaps it is related to the feeling of longing expressed in the words at this point: “Oh Lord I want…”? Many gospel singers would intensify this feeling by lowering the pitch slightly to create an extra-scalar pitch—a so-called “blue note.” Any extra-scalar pitch will appear in the notation as a colored horizontal line without a black line in the middle (either dotted or continuous). We’ll include this at the beginning of our next example.
Here we show the second system of “When the Saints Go Marching In” with the more interesting chords that would probably be used in an actual performance. The melody line is shown in grey so you can compare it with the red for legibility. The bass line is shown as a double black line sounding an octave lower than written (see Counterpoint and Wide pitch range.)
Admittedly, the distinction between melody and chords is not always as clear as this form of notation might suggest: a melody note can always be interpreted as a part of the chord that accompanies it, and it’s often a matter of analytical judgment whether a particular melody note is better understood as a dissonance or an added chord tone. Indeed, the whole exercise of identifying chords with symbols might seem more like analysis than notation. But the answer to that is that any attempt to notate music involves making analytical decisions, whether conscious or intuitive, and what global notation aims to do is to make the basis of such decisions explicit so that what seems “normal” or “natural” in one tradition is not unthinkingly applied to all the others.