- The 4 altered notes are b9 #9 #11 and b13.
- They are located and named in relation to the natural extensions 9 11 and 13 of the dominant seventh chord. For C7 the extensions 9 11 and 13 are the notes D F A. So the altered notes are Db D# F# Ab.
We aren’t fussy about the actual note names, so you could see the enharmonic equivalents C# Eb Gb G# as well!
- These 4 altered notes are often combined with the root 3 and 7 of the dominant to form the ALTERED SCALE ie C Db Eb E Gb Ab Bb C. As you may have noticed, this is also the seventh mode of Db melodic minor.
- However, while the altered scale does a useful job of collecting all the altered notes in one place, we don’t always want to use them all at once. The point of altered notes, after all, is that they are dissonant, colourful and crunchy sounds. We use them both to create interesting colours when heard against particular chords, and as dissonances which need to be resolved by semitone shifts when playing through a cadence. Used properly, the altered notes intensify the colour and momentum of a dominant chord. There is not much joy to be had in dribbling up and down the altered scale in ignorance of these two primary functions…
- Learning how to use the altered notes well takes time - they are more difficult to manage melodically than the chord tones and extensions of the familiar diatonic scale - but before we begin this work we must first learn by heart the 4 altered notes for each dominant seventh - so that we have them at our fingertips.
- How best to learn them? One approach that has helped me is linking the altered notes to the dominant seventh a tritone (b5) away. This makes sense to me because these two dominant sevenths share two essential chord tones (3 and 7). C7 and Gb7, for example, both have the notes E (Fb) and Bb as 3 7 and 7 3 respectively. E and Bb together feels to me to be a sound with two possible values - either C7 or Gb7 - depending on which root I put beneath them. So when I am using the altered notes of C7 (Db Eb Gb Ab) I imagine I am borrowing them from a Gb7 universe, and conversely when I am using the altered notes of Gb7 (G A C D) I imagine I am borrowing them from a C7 universe! Here’s a thing - the altered notes of C7 form the melody of I Got Rhythm in the key of Gb. And the altered notes of Gb7 give the same tune in the key of C!
