Extended Harmony — 9ths, 11ths, 13ths
Extensions add color on top of 7th chords. This week you build 9ths, 11ths, and 13ths — then learn how altered extensions create tension and surprise.
Learning Goals
Lesson Content
Stacking Thirds
Extensions continue the stack: 7th chord plus the 9th (D on top of C7), plus the 11th (F), plus the 13th (A). Each extension is a third above the previous chord tone.
Altered Extensions
A dominant chord can carry b9, #9, #11, or b13 to increase tension before resolving to the tonic. These are the essential ingredients of bebop vocabulary.
Voicing Principles
For clean sound, drop the root and 5th when comping in a jazz context (the bass covers the root). Lead with guide tones (3rd and 7th) and color the voicing with one or two extensions. Rootless voicings keep the texture light.
Practice Activities
Activity 1: Voice Extended Chords on the Synth
On the Synthesizer, play C7, C9, C11, and C13 in order. Then try C7b9, C7#9, and C7alt. Listen for the added color each extension contributes.
Activity 2: Chord Identification — Advanced Mastery
Reach 25 correct with 75%+ accuracy in Chord Identification on Advanced. Train your ear to hear the full range of chord colors.
Activity 3: Chord Reading — Advanced Mastery
Reach 25 correct with 75%+ accuracy in Chord Reading on Advanced. Read extended chord symbols at speed.
Activity 4: Pitch Training — Advanced
Hit 20 correct with 70%+ accuracy in Pitch Identification on Advanced. Sharp pitch recognition is the foundation of hearing extensions.
Activity 5: Interval Mastery Refresh
Reach 20 correct with 75%+ accuracy in Interval Training on Advanced. Extensions are just intervals above the root.