Muze Online: Lesson 15
Chord extensions: 7th, 9th, 11th.
Last week we learnt about chordal harmonisation, using triads. Triads, as we know, are chords made up of three notes: the root, the third, and the fifth. These three notes are all needed to ensure that our chord can be identified, but we can then add extra notes to it to make the harmony richer. These extra notes extend the chord and are often found in jazz. Chord extensions build on the theme of thirds, adding the seventh, the ninth, and the eleventh, even the thirteenth can be introduced. In the diagram below we can see how these extended chords might look in the key of D major and F minor.
The seventh appears often in music of all kinds as part of the cadential progression. When a dominant chord us used before the return to the tonic, adding the seventh to the dominant chord gives the music a greater pull towards the tonic. For example, here is a cadential progression in B major which makes use of a dominant seventh as the penultimate chord:
Note in this example that the dominant seventh (V7) chord is articulated twice, with the second articulation omitting the fifth (C). This is acceptable practise when the seventh is being used.
Follow this link to access a piece of sheet music which makes use of extended harmony. Try and label the extensions.