Voice Leading (The Bach Rules)

When a pianist plays a chord progression, they don’t just jump their hands all over the keyboard. They try to move their fingers as little as possible. This is the art of Voice Leading.

21.1 The Concept of Voices

Even if you are playing solo piano, imagine you are writing for a choir of 4 people:

1. Soprano: The melody (Top note).
2. Alto: Harmony (Middle high).
3. Tenor: Harmony (Middle low).
4. Bass: The foundation (Bottom note).

21.2 The Law of Common Tones

If two chords share a note, keep it in the same voice.

• Example: Moving from C Major (C-E-G) to F Major (F-A-C).
• Bad Way: Lift your whole hand up and move it.
• Good Way: Keep your thumb on C (it’s in both chords). Move E up to F. Move G up to A.
• Result: Smooth, professional sound.

21.3 Forbidden Parallel Fifths

This is the strictest rule in Classical music (though Rock music breaks it constantly).

• The Rule: You should never move the Bass and the Soprano in the exact same interval of a Perfect 5th.
• Why? It sounds “hollow” and makes the two voices lose their independence. They blend into one thick sound instead of two beautiful lines.

---