TETRACHORD is a four-note contiguous scale segment.
It helps to understand the structural relationship of scales by observing the layout of the circular segments as described in
the cycle (circle) of fifths diagram. As you travel counter-clockwise around the circle the key centers move an interval of a
perfect fourth upward, or a perfect fifth downward using clock-wise motion.
The nearest segment to any key center conforms to a natural phenomenon based on the principle of close relations of the
overtone series; for ex., a scale built on F spans an octave and shares its lower 4-notes (tetrachord) with the upper four
notes (tetrachord) key center of B flat, the nearest segment counter-clockwise.
The Circle of fifths diagram shown at left represents the continuous movement of tonic centers that conforms to
the physical vibrations of sound as
sharps are added in the movement around the circle;
This is perceived in a
clockwise direction of flow.
The innermost circle displays the relative Minor key signature that is associated with the particular tonic key in the slice.
It is crucial to an understanding of music theory that this chart be committed to memory.
The success and integrity of modultions and tonicizations used in traditional compositions depends on a firm
understanding of root movements, and even in those cases of the structures
of serial or atonal music the sciene behind TONAL GRAVITY is observed and uilized.
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MODES |
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Modal scales are Western Music’s ‘oldest’ form of scalar patterns, as far as we know. The music of ancient Greece utilized these scales, of which there are seven.
Understanding the modal forms is important, as they contribute to the inventory of music from pre-classical times as well as in modern practice.
Composers have been combining modal forms with major and minor scale patterns for the past century; and modal forms are increasingly common in Jazz.
The "Common Practice Period" label is used to characterize that period of the so-called Classical, Baroque, Romantic and Impressionistic music styles that flourished in Western culture.
ToDo:
Study the diagram below. Notice the extent of the scale patterns that span an octave and the distribution of whole and half steps, which are indicated by the "W" and "H" letters.
Practice on the keyboard or guitar to gain understanding of the characteristic flow of the modal scales.
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INTERVALS |
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Intervals are a measurement of the vertical distance between any two notes
The following table lists all of the standard intervals and their inversions. Notice the pattern:
2nds invert into 7ths
3rds invert into 6ths
4ths invert into 5ths
Major intervals invert into minor intervals
Perfect intervals invert into Perfect intervals
Diminished intervals invert into augmented intervals.
ToDo:
Practice fingering the intervals and their inversions. This will help to develop 'finger' memory.
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COMMON SCALES |
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The following section introduces various scales that are solidly within the inventory of modern practice.
it is recommended that you study/practice these and build simple triads on these scale steps, keeping the tones within the constraints of the scale defined. (see TRIAD section) This exercise will supercharge your development in understanding the concept of "chord-scale compatibility".
1. Jazz scale
A jazz scale is any musical scale used in jazz. Many "jazz scales" are common scales drawn from Western European classical music, including the diatonic, whole-tone, octatonic (or diminished), and the modes of the ascending melodic minor.
All of these scales were commonly used by late nineteenth and early twentieth-century composers such as Rimsky-Korsakov, Debussy, Ravel and Stravinsky, often in ways that directly anticipate jazz practice.
Some jazz scales, such as the bebop scales, add additional chromatic passing tones to the familiar diatonic scales.
One important feature of jazz is what theorists call the principles of chord-scale compatibility
, the idea that a sequence of chords will generate a sequence of compatible scales.
In classical major-mode harmony, chords typically belong to the same scale. (For example, a I-ii-V-I progression in C major will typically use only the notes of the C diatonic collection.)
One chord scale option for +7th chords is the whole tone scale: C D E F# G# A#/B flat
For ex.:
In jazz, a four-chord progression may use four different scales, often as the result of chordal alterations. For instance, in C major, a jazz musician may alter the V chord G-B-D-F with a flattened fifth, producing G-B-Dflat-F. an improviser might then choose a scale containing these four notes, for G whole tone.
II. Bebop scale
Bebop scales add a single chromatic passing tone to the 7 note major scale (Ionian and Mixolydian modes).
The added passing tone creates an 8 tone scale that fits rhythmically evenly within a 4/4 measure of eight 8th notes, thus making it useful in practicing. When an 8th note bebop scale run starts on the beat from a chord tone (Root, 3rd, 5th or ?7th) the other chord notes will also fall on the beats.
As a result all of the "non-chord tones" will fall on the upbeats (the "ands" when counting "one and two and three and four and") and become passing tones.
There are two commonly used types of bebop scales: Dominant bebop scale which adds the raised 7th to Mixolydian: Ascending: 1 2 3 4 5 6 flat7 7 (8) Descending: 8 flat7 6 #6 5 4 3 2 (1) Major bebop scale which adds flat5 to Ionian: 1 2 3 4 5 flat5 6 7 (8)
NOTE: A dominant bebop scale works well over an entire ii V.
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OCTATONIC SCALES |
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There are two types of symmetric diminished scales.
These scales are sometimes called octatonic scales because they utilize eight tones. They are based on a series of alternating half steps and whole steps. One type starts with a half-step (H-W-H-W-H-W-H-W), and one starts with a whole step (W-H-W-H-W-H-W-H).
Because of the repetition of the interval pattern after only two notes, each note in the scale can be a root in another symmetric diminished scale.
For example, the C symmetric diminished scale of the half-step-first type, is composed with the same notes as the half-step-first type Eflat scale, and the whole-step-first type Dflat scale:
C -symmetric (half, whole) diminished: C Db Eb E F# G A Bb C./br>
Eb symmetric (half, whole) diminished:Eb E F# G A Bb C Db Eb.
Db symmetric (whole, half) diminished: Db Eb E F# G A Bb C Db
All three acomposed with the same group of notes: C Db Eb E F# G A Bb C Db Eb E F# G A Bb;
In fact, all symmetric diminished scales are composed with only three groups of notes.
Whole Tone Scales
The Whole tone scale, consisting exclusively of whole steps, is often used on V7+5 chords (C7+ above for example).
Whole tone passages convey the feeling of rootlessness or tonal ambiguity, as the music of the 'Impressionist' composers demonstrate; Ravel, Debussy or some works of Bela Bartok.
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PENTATONIC SCALES |
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Two pentatonic scales common to jazz are the major pentatonic scale and the minor pentatonic scale.
They are both modes to each other, respectively.
The major pentatonic scale begins with a major scale and omits the fourth and seventh scale degrees. The C major scale is
(C, D, E, F, G, A, B); making the C major pentatonic scale (C, D, E, G, A).
The minor pentatonic scale uses the same notes as the Major pentatonic scale, but begins on the sixth scale degree of the
corresponding major scale; so the scale is (A, C, E, D, G).
The minor pentatonic scale replaces the the 2nd scale degree with an augmented 4th followed by the fifth and is commonly known
as a blues scale.
Some chord substitutions involving major pentatonics are:
Over a BbMaj7#11: major pentatonic on 2nd scale degree (CDEAG) implies 9th, 3rd, #11, 13, 7th.
Or, over F#7 using same notes implies b5, b13, b7, b9, and #9.
Whole Tone Scale- showing associated augmented fifth chord (C7#5)
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ALTERED SCALES |
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The harmonic minor scale is also of value to many improvisors, as it provides an alternative color for many common chords and chord progressions. An example is C-D-Eb-F-G-Ab-B-C.
The C harmonic minor scale can be used on C minor tonic, especially on the minor ii V7 i chord progression; an example of chord-scale compatibiity.
Altered Dominant Scale
The altered dominant scale, also loosely called the altered scale, is so named because all the scale members that can be altered relative to the basic dominant scale (the Mixolydian mode), without losing the dominant quality, are altered.
The scale includes both altered ninths (raised and lowered), and both altered fifths (raised and lowered). Starting on C, it contains the notes: C, Db Eb, Fb, Gb, Ab and Bb.
The altered fifths coincide enharmonically with the sharp eleventh and the flat thirteenth which would also be considered altered relative to their Mixolydian forms. The tonic, major third, and dominant seventh are retained as essential to the dominant quality.
The scale can also be understood as a mode of the ascending melodic minor scale starting from the 7th scale degree. For a C7 chord, the C# melodic minor scale starting from B# (C enharmonically) produces the C altered dominant scale enharmonically.
Another name for this scale is the diminished-wholetone scale because the first tetrachord is that of a (half, whole) diminished scale and the second tetrachord is whole-tone (or locrian).
ToDo:
Study and practice playing all these scale patterns until you feel comfortable in your understanding of them-then practice some more.