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Acoustic scale
Modes	I, II, III, IV, V, VI, VII
Component pitches
	C, D, E, F♯, G, A, B♭
Qualities
Number of pitch classes	7
Forte number	7-34
Complement	5-34

In music, the acoustic scale, overtone scale,^[1] Lydian dominant scale (Lydian ♭7 scale),^[2]^[3] or the Mixolydian ♯4 scale is a seven-note synthetic scale. It is the fourth mode of the ascending melodic minor scale.^[4]^[5]

${ \override Score.TimeSignature #'stencil = ##f \relative c' { \clef treble \time 7/4 c4^\markup { Acoustic scale on C } d e fis g a bes c } }$

This differs from the major scale in having an augmented fourth and a minor seventh scale degree. The term "acoustic scale" is sometimes used to describe a particular mode of this seven-note collection (e.g. the specific ordering C–D–E–F♯–G–A–B♭) and is sometimes used to describe the collection as a whole (e.g. including orderings such as E–F♯–G–A–B♭–C–D).

History

In traditional music, the overtone scale persists in the music of peoples of South Siberia, especially in Tuvan music. Overtone singing and the sound of the Jew's harp are naturally rich in overtones, but melodies performed on the igil (bowed instrument distantly related to the violin) and plucked string instruments such as the doshpuluur or the chanzy also often follow the overtone scale, sometimes with pentatonic slices.^{[clarification needed]}

The acoustic scale appears sporadically in nineteenth-century music, notably in the works of Franz Liszt and Claude Debussy.^[6] It also plays a role in the music of twentieth-century composers, including Igor Stravinsky, Béla Bartók,^[7] and Karol Szymanowski, who was influenced by folk music from the Polish Highlands.^[8] The acoustic scale is also remarkably common in the music of Nordeste, the northeastern region of Brazil^[9] (see Escala nordestina). It plays a major role in jazz harmony, where it is used to accompany dominant seventh chords starting on the first scale degree. The term "acoustic scale" was coined by Ernő Lendvai in his analysis of the music of Béla Bartók.^[10]

Construction

The name "acoustic scale" refers to the resemblance to the eighth through 14th partials in the harmonic series (Play^ⓘ). Starting on C₁, the harmonic series is C₁, C₂, G₂, C₃, E₃, G₃, B^♭
₃^*, C₄, D₄, E₄, F
₄^*, G₄, A^♭
₄^*, B^♭
₄^*, B₄, C₅ ... The bold notes spell out an acoustic scale on C₄. However, in the harmonic series, the notes marked with asterisks are out of tune: F
₄^* (Play^ⓘ) is almost exactly halfway between F^♮
₄ and F^♯
₄, A^♭
₄^* (Play^ⓘ) is closer to A^♭
₄ than A^♮
₄, and B^♭
₄^* is too flat to be generally accepted as part of an equal tempered scale.

The acoustic scale may be formed from a major triad (C E G) with an added minor seventh and raised fourth (B^♭ and F♯, drawn from the overtone series) and major second and major sixth (D and A).^[10] Lendvai described the use of the "acoustic system" accompanying the acoustic scale in Bartók's music, since it entails structural characteristics such as symmetrically balanced sections, especially periods, in contrast with his use of the golden ratio. In Bartók's music, the acoustic scale is characterized in various ways including diatonic, dynamic, tense, and triple- or other odd-metered, as opposed to the music structured by the Fibonacci sequence which is chromatic, static, relaxed, and duple-metered.^[10]

Another way to regard the acoustic scale is that it occurs as a mode of the melodic minor scale starting on the fourth degree. Hence, the acoustic scale starting on D is D, E, F^♯, G^♯, A, B, C, D, containing the familiar sharpened F and G of A melodic minor. The F♯ turns the D minor tetrachord into a major tetrachord, and the G♯ turns it Lydian. Therefore, many occurrences of this scale in jazz may be regarded as unsurprising; it shows up in modal improvisation and composition over harmonic progressions which invite use of the melodic minor.

Notes

^ These may be approximated by the nearest quartertone at A or B for the harmonic seventh, but since ⁠7/4⁠ is 968.826 cents, it is 18 cents or almost a whole comma sharp from the quartertone. The eleventh harmonic F or G is nearly spot-on the quartertone at 551.318 cents.

References

^ Persichetti, Vincent (1961). Twentieth-Century Harmony. New York City: W. W. Norton & Company. p. 44. ISBN 978-0-393-09539-5. OCLC 318260658.
^ Berle, Arnie (1997). "The Lydian Dominant Scale". Mel Bay's Encyclopedia of Scales, Modes and Melodic Patterns: A Unique Approach to Developing Ear, Mind and Finger Coordination. Pacific, Missouri: Mel Bay Publications. p. 55. ISBN 978-0-7866-1791-3. OCLC 48534968.
^ Fewell, Garrison (February 1998). "Sessions: Lydian-Dominant Strategies". Guitar Player. 32 (2): 154–155.
^ Lendvai, Ernő (1971). Béla Bartók: An Analysis of his Music. introd. by Alan Bush. London: Kahn & Averill. p. 27. ISBN 0-900707-04-6. OCLC 240301. Cited in Wilson, Paul (1992).
^ Bárdos, Lajos cited in Kárpáti 1994, 171^{[incomplete short citation]}
^ Tymoczko, Dmitri (2004). "Scale Networks in Debussy." Journal of Music Theory 48.2: 215–292.
^ Tymoczko, Dmitri (2003). "Stravinsky and the Octatonic: A reconsideration." Music Theory Spectrum 25.1: 185–202.
^ "Classical CD Reviews: Folk music, mythology inspire Polish composer's violin pieces", The Dallas Morning News, October 13, 2007
^ Adolfo, Antonio (1997). Composição, Uma discussão sobre o processo criativo brasileiro. Rio de Janeiro: Lumiar Editora. p. 23. ISBN 978-85-7407-369-9.
^ ^a ^b ^c Wilson, Paul (1992). The Music of Béla Bartók, p. 7. ISBN 0-300-05111-5.
^ Miller, Leta E., ed. (1988). Lou Harrison: Selected keyboard and chamber music, 1937–1994. p. $xliii$ . ISBN 978-0-89579-414-7.