Extended

Extended chords are 5 tone chords that are extended past the 7th

• ex. 9th, 11th, 13th

They are called compound because they are greater than one octave

Compound chords are played with the 7th.

• this is the principal difference between an add2 (aka add9) chord and a 9th chord

Recall that added dissonance results when a note is added to a chord that is a semitone away from an existing chord tone. For this reason, we will notice that major 9 chords are less dissonant than major 13 chords, since the 9 chord contains a 1-2-3-5-7, while the 13 chord contains 1-3-4-5-7 (the 4 is a semitone away from the 3, resulting in the dissonance in the later).

Variants:

• dominant (ie. standard) extended chords
  • major triad + dom7 + extension note
  • ex. C11
• major extended
  • major triad + dom7 + extension note
  • ex. Cmin11
• minor extended
  • minor triad + maj7 + extension note
  • ex. Cmaj11
• augmented extended
  • ex. C9♯11 (major triad, dom7, regular 9, sharp 11)
  • ex. Cmaj9♯11 (major triad, maj7, regular 9, sharp 11)

Tension in extended chords can be increased by flattening or sharpening the extension note

• these could be termed "non-vanilla", since they introduce notes outside of the key

Eleventh (11th)

In dominant 11th chords (ie. standard 11th chords), typically the 9th is omitted

• this is not the case for maj11 chords or m11 chords, since the dissonant interval is not created
  • recall that maj11 means a major 7th is used, whereas m11 means minor 3rd is used

A perfect eleventh creates a highly dissonant minor ninth interval with the major third of major and dominant chords. To reduce this dissonance the third is often omitted

• a dominant eleventh chord can be heard 52 seconds into the song "Sun King", turning the chord into a suspended ninth chord (e.g. C9sus4, C–G–B♭–D–F), which can be also notated as Gm7/C.

Creating the chord on piano

To create an 11th chord (with 3rd omitted), simply:

• with left hand, play root octaves or 1-5
• with right hand, play major triad that is a whole tone down from the root

For example, C11 is formed by playing C in the bass and a Bb major triad on top

• Bb because Bb is a whole tone down from C

Thirteenth (13th)

Typically, 13th chords omit the 9th AND the 11th

Most commonly, 13th chords serve a dominant function (V13), whether they have the exact intervals of a dominant thirteenth or not.

• Typically, a dominant chord anticipating a major resolution will feature a natural 13, while a dominant chord anticipating a minor resolution will feature a flat 13

A thirteenth chord does not imply the quality of the ninth or eleventh scale degrees. In general, what gives a thirteenth chord its characteristic sound is the dissonance between the flat seventh and the thirteenth, an interval of a major seventh (ie. octave minus 1 semitone).

Creating the chord on piano

To create a 13th chord, simply:

• play the root and 3rd in the left hand
• add in the 7th and one semitone less than an octave of that 7th

For example, C13 is formed by play C and E in the left hand, and in the right, play Bb (the 7th) and A (the 13th)

• note: the Bb and the A are octave minus 1 semitone apart. This makes it easy to visualize the interval between the 7th and the 13th.