Other Guide Tones
Although the 3rd and 7th of a chord are the most common guide tones, there are other notes in various types of chords which can be important in indicating the particular chord type. In triads, this can be the 5th, which can indicate a diminished or augmented chord when combined with the 3rd of the chord.
In the following example, the piano in the first two bars plays a C root note and a minor 3rd (Eb) while the saxophone alternates between the 5th (G) and the flat 5th (Gb) to indicate first a minor chord and then a diminished chord.
In the third and fourth bars, the piano plays the C root note and a major 3rd (E) while the sax alternates between the 5th (G) and the sharp 5th (G#) to indicate first a major chord and then an augmented chord.
In 6th chords, the 6th degree is a guide tone as demonstrated in the following example.
All the upper extensions of a chord (9ths, 11ths and 13ths) can also be used as guide tones as shown in the following example. Notice that the 13th degree is the same as the 6th. However, the presence of the 7th degree in the chord tells you that it is a 13th because in a 6th chord, the 6th degree is used instead of the 7th.
The more notes there are in a chord, the more possible guide tones it contains. In a seventh chord, there are two but anything higher contains three. The fact that there are more guide tones can make it easier to create a smooth line between chord changes. In the following example, the sax plays one note (G) while the chords change under it. This note begins as the 3rd of Ebmaj7, then becomes the 4th of Dsus7, then the 9th of F9, and finally the 13th of Bb13.
