Cargos asociados a los costes del sistema

c c

w

C

w

w b

Cm

w

When improvisers wish to be clear about the harmonic progression, they aim for the thirds over the roots played in the bass lines. Hank Mobley aimed for thirds in the example below. Mobley landed on the third of Gm (B

b

) and Cm7 (E

b

) without any preparation. The third of F (A) was approach by ascending scale steps. The third of the Dm7 (F) was approached from an upper neighbor. The third of G (B

n

) was delayed until beat four, and the third of Cm (E

b

) was delayed until beat three.

9.14

& b b c œ Œ

^B

^b

^œGm7j

˙

œ œ œ œ Œ ‰ Jœ

Cm7 F7

œ œ œ œ œ œ œn œ

Dm 7 G7

œ œn œ œ Jœ

Cm 7

LINEAR IMPLICATIONS of HARMONY

What is meant by the term “chord changes?” It usually refers to a given chord progression or the writ-ten chords symbols. In any progression, some notes change between two adjacent chords and some pitches stay the same. Chord changes in the truest theoretical and aural sense refers to the notes that change between two chords. Melodic lines can emphasize the notes that stay the same or the notes that change. If a melodic line is to create the sense of harmonic motion, it must address the notes that change. A player who is “making the changes” addresses the notes that identifies the chords (consonant notes: usually thirds) and finds the notes that move one chord to the next (dissonant notes that often pull towards the consonant thirds). The voices that lead to the next voice follow certain principles. Any pitch that is played over a harmonic progression has linear implications.

Guide tone lines may be created by following the given voice leading lines implicated by the harmonic progressions. The guide tone lines are easy to hear and listeners intuitively follow them with a set of

ex-pectations. Melodic inventiveness is a result of manipulation, elaboration, rhythmic enhancement, and playful departure from these paths.

When the roots of chords in a progression move in descending fifths, the most common root move-ment, it suggests specific voice leading principles. The voice leading principles can be stated simply:

• Thirds resolve to sevenths

• Sevenths resolve to thirds

• Fifths resolve to ninths

• Ninths resolve to fifths 9.15

& c ˙ ˙

Dm 7 G7

3 7

w

C

3

˙ ˙

Dm7 G7

5 9

w

C

5

˙ ˙

Dm7 G7

7 3

w

C

7

˙ ˙

Dm 7 G7

9 5

C

w

9

There may be some variants on dominant chords.

• The ninths may be altered, so the

n

_9,

b

_{9 or}

#

9 (usually shown as its enharmonic equivalent) may be used. Any of the three ninths would still resolve to the fifth of the subsequent chord as shown below. The

b

_{9 and}

#

9 pitches are associated with minor keys though they are freely used in major keys to create more tension. The A

b

_{and B}

b

pitches shown below could be from the key of C minor, three flats.

• The fifth of a dominant chord may be replaced by a

n

_{13 or a}

b

_{13, the}

#

_{11 or}

b

5. Any of these substitute pitches behave as a fifth and resolve to the ninth of the subsequent chord. The

b

₁₃

is associated with a V7 in minor as the

b

13 is the minor third of the key. The E

b

below could be from the key of C minor, three flats.

9.16 Dominant Variants

#

_{9 or}

b

_{9 for}

n

₉

n

_{13 for}

n

₅

b

_{13 for}

n

₅

#

_11/

b

_{5 for}

n

₅

& c ˙ œ b œ b

Dm 7 G7

w

C ^Dm7

˙

^G7

˙

^C

w

^{Dm7 G7}

˙ b ˙

^C

w ˙ ˙ #

Dm 7 G7 C

w

Not all voices change between chords. When ninth chords are moving in a typical cycle of fifths pro-gression, the roots in the bass change for each chord. Alternating pairs of voices resolve down stepwise.

The E and C of the Dm9 move to the D and B of the G9 chord while the A and F remain stationary.

Then the A and F of the G9 move to the G and E of the Cmaj9 while the D and B remain stationary.

9.17 Pairs of voices alternating motion

An experienced improviser need not depend on a rhythm section accompanist to supply the harmonic foundation (or the time). Harmony can be supplied as counterpoint between the single note bass against the single note melodic line. This can be accomplished by aiming for a consonant melodic pitch, usually the major or minor third, that clarifies the chord quality and then moving to a dissonant note that creates motion by wanting to resolve to the consonant pitch for the next chord. The chord tone that most often generates the motion to the next chord is the seventh. The seventh needs to re-solve down, and when it does and the bass moving down by fifths, then the seventh will rere-solve to the third of the next chord.

In this ii7 - V7 - I progression, the consonant note F, the third of the D minor, becomes the dissonant note over the G7, then resolves down to the consonant third of C major. This is a basic guide tone line.

9.18 Basic Guide tone line beginning on third:

&

The more elaborate melodic line in ex. 9.19 follows the basic guide tone line shown from ex. 9.18. The F is approached using scale tones. The high and low points of the Dm7 measure are chord tones with G as a passing tone. The E and the G on beat four point to the F of the G7 measure. After a large leap from F to E, which is a step disguised by octave displacement, the step motion continues down the scale. The last four notes preceding the E are a broken arpeggio of a G7 chord. The F, the dissonant seventh, is saved for last to propel the line towards the E, the third of C.

9.19 More elaborate line based on Guide tone line:

& c œ œ œ œ œ œ œ œ œ œ

To create a guide tone line with more motion, the third may move to the seventh of the D minor chord which will resolve to the third of the G7 chord. The seventh of the G7 chord resolves to the third of the C major. Each measure begins with a stable tone, moves to a dissonant tone and resolves over the mea-sure line to a stable tone again.

9.20

A bass line follows a guide tone line of roots in a fairly strict fashion: using quarter note rhythms and landing on roots on the beat one of a measure. There is more freedom in the development of melodic lines from their guide tones: the range of rhythmic variations is endless; the line can be embellished with many more diatonic and chromatic notes; and the guide tones are not restricted to the downbeats of measures. As long as the identifying pitches happen at significant places in the measure they will serve their function in the melodic line.

The two lines below were improvised by Tom Harrell and followed the guide tones shown above. In ex.

9.21 the F did not occur on the downbeat and was approached from above. The G

b

did not sound like an F

#

, the major third of D; it sounded like a chromatic passing tone. The C, the dissonant seventh, oc-curred just before beat four, so to avoid reaching the B

n

too early, Harrell approached the B from below using a chromatic passing tone (A - A

#

). After playing notes borrowed from the parallel key of C minor (E

b

, A

b

, and B

b

), Harrell played the seventh of G7 which resolved to the E on the downbeat of the Cmaj7 measure. In ex. 9.22, Harrell approached the F from below using scale steps, the D was surrounded by its upper and lower neighbors, followed by a leap past and then back to the dissonant C. The C resolved to the B which Harrell placed on the strong first and third beats separated by chromatic and diatonic passing tones. The line continued down the diatonic scale with the dissonant F resolving to the E over the bar line. Both of these examples illustrate how flexible a line can be and still incorporate the guide tones.

9.21 Improvised lines that follow guide tone lines:

& c œ œ b œ œ œ œ œ œ #

The necessary notes for modulation, which should be committed to memory, will now be helpful in de-termining guide tone lines and melodic pitches. The progression in ex. 9.23 is I - ii7/IV - V7/IV - IV. A B

b

is needed to modulate from the key of C to the key of F major. What important pitch should be the guide tone to lead to the key of F over these chords? B

b

, the necessary accidental. What is the most con-sonant pitch that will identify the G minor chord? B

b

, the third of Gm7. What pitch creates the most mo-tion from the C7 chord which will point to the Fmaj7 chord? B

b

, the seventh of C7 which points to the A, the consonant third and identifying pitch of F major. If one can tell that a tune has modulated or temporarily tonicized another key area, it is because somewhere in the music the accidentals necessary

for modulation have been used to point away from the tonic key. The guide tones lead the listener to the

If one can tell that a tune has modulated or temporarily tonicized another key area, it is because somewhere in the music accidentals necessary for modulation have been used to

point away from the tonic key. The guide tones lead the listener to the new key area.

In document Análisis técnico y económico del impacto de las instalaciones de autoconsumo en las redes eléctricas : aplicación a la generación fotovoltaica integrada con recursos energéticos distribuidos (página 56-59)