Learn to improvise. 2004-2005. Lesson 08: ambiguity and replacement of chords.

When we have more experience we may extend the number of positions of the chords.

A thumb rule is to spread the bass notes, as they will growl if they are close to each other. This is caused by the over tones being in the audible range.
G7 in position d-f-g-b in different octaves.

These overtones may be used to replace a major triad by only the root note of the chord in the bass. E.g. the first 6 overtones of note c are c g c e g c.
Chords replaced by bass notes.

The dissonance of high notes close together is more pronounced if they are not masked by surrounding notes. E.g. chord G7 may be replaced by the two notes f5-g5.
The root and seventh note of seventh chords close together.

In this example we use the right hand to make the chord. In the beginning we took the chords in the left hand and made the melody with the right one. Sometimes it is interesting to interchange and mix these tasks. (Think of the works of Bach)
Right hand plays the greater part of the chord.

We have seen added notes for the chords of big bands, but it also may be fascinating not to play the chords but to suggest them. E.g. by first playing a song with the chords and directly afterwards to suggest the harmonic flow by choosing the right single notes.
Verse of Guilty, first with chords and directly afterwards with only accompanying notes.

Another application of leaving notes out of chords is the ambiguity. By playing the notes c-g in stead of the chords C or Cm we leave undecided which of the two is meant.
Left hand has only the notes c-g and f-c.
Perhaps the harmonic or melodic flow will solve that, but if not it may give an entertaining tension. In compositions ambiguity is always intentional. The phenomenon is known in every art.

We also may replace chords by other ones influencing the style and atmosphere but leaving the harmonic flow as it is. Often these have only one note different of the original primary chord. Examples are: a dim7 replacing a seventh chord, Am replacing C, Dm replacing F, C6 (=Am7) replacing C or Am, Cmaj7 replacing C, and Em replacing C.

In the key of C the subdominant is in the jazz usually F7, but it may also be played as F, F6, F9, Fm, Fm7, Fmaj7, Dm, Cdim, Cdim7, Ab7, and maybe as Eb7.
Subdominant in succession: F7, F, F6, F9, Fm, Fm7, Dm, Cdim7.

The changing of the chords and the division of the tasks over both hands may not only be used to influence the style and atmosphere, but also to simplify and get a more flowing play. Chords must not be brought like a slide show but like a movie. Timing is the basis of music. In order to improve that, notes may be ignored. It may not only simplify but a melodic accompaniment is more flowing than one by chords. It may be a walking bass, a second part, or a single note of the accompanying chord. In the left hand broken G7 als g-d-f is easier to change with C as g-c-e than G7 as g-b-d-f.
Bass lines are easier than chords and more flowing.

A general reason is that stuffing does not give evidence of good taste. It may be interesting to leave something to do for the imagination of the listener. The polyphonic compositions of Bach are highly esteemed.
HOMEWORK: Experiment with replacing of chords.
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