Tonal Functions and Voice Leading
The tritone as tension engine, T/SD/D functions, and the rules of 4-voice counterpoint.
Brahms was obsessed with the purity of four-voice writing. He hunted parallel fifths and octaves as absolute offences against taste, marking his students' scores in red. He said th…
À retenir : Voice leading is the art of making each melodic line independent and fluid.
The tritone — engine of harmonic tension
The tritone is the interval of 3 whole tones (6 semitones) that forms naturally between the 4th and 7th degrees of a major scale. In C major: F and B. Its acoustic instability is the engine of all tonal harmonic tension.
Why does the tritone create tension?
The tritone divides the octave into two equal halves (6+6 semitones). This perfect symmetry deprives it of natural direction — it does not know where to go. The ear perceives this ambiguity as tension that must resolve.
Chord classification relative to the tritone
| Function | Tritone notes | Character | Examples in C |
|---|---|---|---|
| Tonic (T) | Neither F nor B | Stable, rest | C, Am |
| Subdominant (SD) | F only | Prepares | Dm, F |
| Dominant (D) | F and B | Maximum tension | G7, Bdim |