Weak beat non-chord tones are the most common kinds of decorative dissonance. They usually sound lighter than strong-beat NCTs because the dissonant note falls on a weak or relatively weak part of the measure. But metric placement is only one part of the story. To identify a non-chord tone, ask three questions: where does the dissonance fall, how is it approached, and how does it resolve?
Every NCT has three moments: the approach, the NCT itself, and the resolution. Weak-beat NCTs share the general pattern of placing the dissonance away from the strongest beat, but they differ in melodic shape. Some move by step, some leap, some return to the same chord tone, and some anticipate the next harmony.
| Type | Usual approach | Usual resolution | Basic effect |
|---|---|---|---|
| Passing tone | Step | Step in same direction | Fills in a third |
| Neighbour tone | Step | Step back to the same chord tone | Leaves and returns |
| Anticipation | Usually step or repeated tone | Becomes chord tone in next harmony | Arrives early |
| Incomplete neighbour | Leap or step | Step or leap, usually asymmetrical | Decorates by imbalance |
| Escape tone | Step | Leap in opposite direction | Escapes from the line |
| Changing tone pattern | Step, then leap | Returns to original chord tone | Two-note neighbour pattern |
Passing Tone
The passing tone (or passing note) is the most common type of non-chord tone. A passing tone literally passes between 2 different chord tones. A passing tone can pass between 2 chord tones of the same chord or between 2 chord tones of different chords. Passing tones fall on weak or relatively weak beats. The passing tone itself moves by step (a 2nd), filling in the interval of a 3rd between the two chord tones.
Sometimes there will be two passing tones in a row; this is very common when moving between the 5th of the chord up to the root above: sol-la-ti-do.
Neighbour Tone
A neighbour-tone (or auxiliary-tone) is a non-chord tone that falls between two chord-tones that are the same note. A neighbour-tone can pass between two chord tones of the same chord or between 2 chord tones of 2 different chords. The neighbour can be above or below the chord-tones. Because the line leaves a chord tone and returns to the same chord tone, the larger melodic journey begins and ends in the same place.
Anticipation
An anticipation arrives early on a pitch belonging to the next chord, then repeats or continues as that chord begins. It may be approached by step or leap.
Example: ABBA, Waterloo (1974).
Incomplete Neighbour
An incomplete neighbour is approached by a leap and then resolved by step to the chord tone (or vice versa - approached by step and resolved by leap).
Escape Tones
An escape tone (or échappée) is approached by step and left by leap in the opposite direction. The inverse contour belongs to the incomplete-neighbour family; historical uses of cambiata vary.
Changing Tone Pattern
A changing tone pattern is a pair of non-chord tones appearing between the same start/end note. Start on a chord note and then move to a neighbour tone and then leap to the other neighbour tone before returning to the original note.
Example: The Beatles, Let It Be (1970) has changing tones.
