3850 / 18210 · Workshop 20 — “I Got Rhythm” / Rhythm Changes: AABA Form, Fast Turnarounds, Dominant Chains, and Thinking One Phrase Ahead← prev⊞ allnext →
20.69Level 36 — chord-scale economy
On A sections in B♭:
much of the melodic language can still derive from B♭ major plus altered notes required by secondary dominants.
Example:
G7 requires B natural.
Otherwise you may remain close to B♭-major vocabulary.
That is simpler than switching theoretical scales constantly.