13792 / 18210 · Workshop 107 — Composing Inner Voices and Counterpoint: Making the Middle of the Texture Carry Meaning Instead of Merely Filling Chords← prev⊞ allnext →
107.51Level 39 — tritone substitution shared guide tones
G7:
B-F.
D♭7:
C♭(=B)-F.
They share:
B/F enharmonically.
So an inner guide-tone pair can remain while bass changes:
G→D♭.
This explains the substitution sonically.