Altered scale

From Wikipedia, the free encyclopedia

In jazz, the altered scale is a seven-note scale that differs from the locrian mode in having a lowered fourth scale degree. Starting on C, it contains the notes: C, Db, Eb, Fb, Gb, Ab and Bb. (This is the C locrian mode, C-Db-Eb-F-Gb-Ab-Bb, with F changed to Fb. For this reason, the altered scale is sometimes called the "super locrian mode.") It is the seventh mode of the melodic minor ascending scale. The scale is sometimes spelled with two thirds rather than a flatted fourth scale degree--e.g. C-Db-Eb-E-Gb-Ab-Bb, with E substituting for Fb. In contrast to the term acoustic scale, the term "altered scale" almost always refers to this particular mode of the melodic minor, rather than the scale itself. In this sense, the term "acoustic mode" would be more accurate.

The acoustic scale appears sporadically in the works of Debussy and Ravel (Tymoczko 1997), as well as in the works of recent composers such as Steve Reich (see, in particular, the Desert Music). It plays a fundamental role in jazz, where it is used to accompany altered dominant seventh chords starting on the first scale degree. (That is, the scale C-Db-Eb-E-Gb-Ab-Bb is used to accompany chords such as C-E-Gb-Bb, the "dominant seventh flat five" chord.

The C altered scale consists of the notes

C D-flat E-flat F-Flat G-flat A-flat B-flat C

One way to obtain the altered scale is by raising the tonic of a major scale by a half step; for example, when we raise the tonic of the B major scale, which has the notes

B C-sharp D-sharp E F-sharp G-sharp A-sharp B

we get the C altered scale

C C-sharp D-sharp E F-sharp G-sharp A-sharp C

the notes of which are enharmonic (identical, in the equal temperament system) with the notes of the C altered scale as it was first described on this page.

Like the other modes of the melodic minor ascending, the altered scale shares six of its seven notes with an octatonic (or "diminished") scale, and five of the six notes of a whole tone scale. (For example, the altered scale C-Db-Eb-E-Gb-Ab-Bb shares all but its Ab with the octatonic scale C-Db-Eb-E-F#-G-A-Bb; while sharing five of the six notes in the whole-tone scale C-D-E-Gb-Ab-Bb.) This accounts for some of its popularity in both the classical and jazz traditions (Callender 1998, Tymoczko 2004).

[edit] Sources

• Callender, Clifton. "Voice-leading parsimony in the music of Alexander Scriabin." Journal of Music Theory, Vol. 42, No. 2, Neo-Riemannian Theory, (Autumn, 1998), pp.

219-233.

• Tymoczko, Dmitri. “The Consecutive-Semitone Constraint on Scalar Structure: A Link Between Impressionism and Jazz.” Integral 11 (1997): 135–179.
• Tymoczko, Dmitri. “Scale Networks in Debussy.” Journal of Music Theory 48.2 (2004): 215-292

[edit] External links

• The altered scale for guitar

Musical scales by	edit
# | pentatonic | hexatonic | heptatonic | octatonic | chromatic
Types | Altered | Bebop | Diatonic scale | Enharmonic | Jazz scale | Minor scale
Name | Acoustic | Blues | Bohlen-Pierce | Diatonic | Double harmonic | Half diminished | Harmonic major | Lydian dominant | Major | Major locrian | Pelog | Phrygian dominant scale | Slendro
"Ethnic" name | Arabic | Gypsy | Jewish

Modes of the diatonic scale	edit
Ionian (I) | Dorian (II) | Phrygian (III)
Lydian (IV) | Mixolydian (V) | Aeolian (VI) | Locrian (VII)

Modes of the melodic minor scale	edit
Melodic minor (I) | Dorian b2 (II) | Lydian Augmented (III)
Lydian Dominant (IV) | Mixolydian b13(V) | Locrian #2 (VI) | | Altered (VII)