Question: What is the definition of the following?
1. Tendency tone
2. Stable tone
3. Active toneTimothy (Ibadan, Oyo, Nigeria)
Albert's reply: These are harmonic terms having specifically to do with melody writing and voice leading. Let's take stable tones first. These are the tones of the tonic triad, scale degrees 1, 3 and 5.
For example, in C major:
... the notes C, E and G (scale degrees 1, 3 and 5) are stable tones. They don't "need" to move anywhere.
The tonic—the first note of the scale—is the most stable tone, followed by scale degrees 3 and 5.
Tendency tones and active tones are synonymous. These are the other scale degrees: 2, 4, 6 and 7.
Scale degrees 2, 4 and 6 resolve downward: Scale degree 2 "wants" to resolve to 1; 4 wants to resolve to 3, and 6 to 5.
Scale degree 7—called the leading tone when it is a half-step below the tonic—is the exception in that it resolves upward to the tonic.
You can visualize (and play) the tendency (active) tones and their resolutions to stable tones using this illustration:
Remember that these are mere guidelines that are useful for analyzing music, melody writing and improvising. No musical rule is absolute!