Relationship Between Scales And Chords
There is a hidden link between chords and scales that is important to recognize and understand. Especially within the musical style of jazz, sevenths and upper extensions are included in chord voicings. There is an experiment we can conduct on the piano, since it is a very visual instrument (keys laid out in front of us), to display the relationship between scales and chords. If we were to play the four pitches of a seventh chord in root position with our left hand, we will see a pattern of stacked thirds. If we then add the 9th, 11th and 13th to this chord with our right hand we continue the pattern of stacked thirds even higher. However, if we move our right hand down an octave, it is now playing the notes located between the pitches of the left hand. The result is that our two hand are depressing seven consecutive pitches within an octave, or a scale. This scale is a logical pool of pitches for improvisation over its corresponding chord.
Why Use Both?
Musical melodies are composed of static motion, stepwise motion and jumps. The key to constructing a beautiful and interesting melody is using a proper balance of these types of motion. Too much of any one type of motion will cause the melody to sound like an exercise and not a musical line. Static motion does not require a pool of pitches since it involves only one pitch. However, actual motion will tend to resemble this "exercise" effect when only one mindset (scales or chords) is applied to the improvisation construction. When we learn to flip between these mindsets we can alternate between scale and arpeggio like passages in our improvisation. This approach brings balance to the melodies we create and causes them to sound more melodic. This balance is further enhanced when we contrast the direction of the motion (leap up followed by a scale down or scale up followed by leap down).
Why Use Neither?
True melodic phrases express ideas that are identifiable and memorable. This is the component of a well constructed melody that brings it to life. John Williams used this concept to connect certain melodies with the identity of characters in his soundtrack for Star Wars (a technique used by Stravinsky and other great composers). If we concentrate only on combining and contrasting scales, arpeggios and static motion we will construct lifeless melodies. The audience will be lost in a sea of pitches with no identifiable or memorable reference points to anchor their ears. For this reason, it is most effective to start with the mindset of creating motifs. While creating these melodic (or rhythmic in the case of static motion) motifs we draw form the pools of scale and arpeggio collections. However, these scales and arpeggios only serve to aid our construction of the motif. We are not looking to utilize every pitch in the collection, only those that form the memorable melodic idea we wish to express. Through transposition, inversion and other devices of variation one motif can be transformed into several bars of interesting melodic content.
Beginning students play notes, but musicians play music. This statement is true for both the performance of written music and improvisation. The only difference is that improvisation combines the skills of performance and composition into an instant art of musical creative expression. The proper focus of melodic identity composed with varying types of melodic motion will ensure that our improvisation maintains its musical life and expression.