17 equal temperament

{{short description|Musical tuning system with 17 pitches equally-spaced on a logarithmic scale}}

File:Rank-2 temperaments with the generator close to a fifth and period an octave.jpg

{{stack|File:1 step in 17-et on C.mid}}

In music, 17 equal temperament is the tempered scale derived by dividing the octave into 17 equal steps (equal frequency ratios). Each step represents a frequency ratio of {{radic|2|17}}, or 70.6 cents.

17-ET is the tuning of the regular diatonic tuning in which the tempered perfect fifth is equal to 705.88 cents, as shown in Figure 1 (look for the label "17-TET").

History and use

Alexander J. Ellis refers to a tuning of seventeen tones based on perfect fourths and fifths as the Arabic scale.Ellis, Alexander J. (1863). "On the Temperament of Musical Instruments with Fixed Tones", Proceedings of the Royal Society of London, vol. 13. (1863–1864), pp. 404–422. In the thirteenth century, Middle-Eastern musician Safi al-Din Urmawi developed a theoretical system of seventeen tones to describe Arabic and Persian music, although the tones were not equally spaced. This 17-tone system remained the primary theoretical system until the development of the quarter tone scale.{{Citation needed|date=September 2015}}

Notation

File:17-tet scale on C.png{{cite journal|last=Blackwood|first=Easley|author-link=Easley Blackwood Jr.|date=Summer 1991|jstor=833437|title=Modes and Chord Progressions in Equal Tunings|journal=Perspectives of New Music|volume=29|number=2|pages=166–200 (175)|doi=10.2307/833437 }} for 17 equal temperament: intervals are notated similarly to those they approximate and enharmonic equivalents are distinct from those of 12 equal temperament (e.g., A{{music|#}}/C{{music|b}}).File:17-tet scale on C.mid]]

Easley Blackwood Jr. created a notation system where sharps and flats raised/lowered 2 steps.

This yields the chromatic scale:

:C, D{{music|flat}}, C{{music|sharp}}, D, E{{music|flat}}, D{{music|sharp}}, E, F, G{{music|flat}}, F{{music|sharp}}, G, A{{music|flat}}, G{{music|sharp}}, A, B{{music|flat}}, A{{music|sharp}}, B, C

Quarter tone sharps and flats can also be used, yielding the following chromatic scale:

:C, C{{music|t}}/D{{music|flat}}, C{{music|sharp}}/D{{music|d}}, D, D{{music|t}}/E{{music|flat}}, D{{music|sharp}}/E{{music|d}}, E, F, F{{music|t}}/G{{music|flat}}, F{{music|sharp}}/G{{music|d}}, G, G{{music|t}}/A{{music|flat}}, G{{music|sharp}}/A{{music|d}}, A, A{{music|t}}/B{{music|flat}}, A{{music|sharp}}/B{{music|d}}, B, C

Interval size

Below are some intervals in {{nobr|17 {{sc|EDO}}}} compared to just.

File:Major chord on C.png on C in {{nobr|17 {{sc|EDO}} }}: All notes are within 37 cents of just intonation (rather than 14 cents for {{nobr|12 equal temperament}}).

style="margin:1em auto;"

| {{nobr|17 {{sc|EDO}}}}

File:Major chord on C in 17 equal temperament.mid
justFile:Major chord on C in just intonation.mid
{{nobr|12 equal temperament}}File:Major chord on C.mid

]]

File:Simple I-IV-V-I isomorphic 17-TET.png in {{nobr|17 {{sc|EDO}}}}.{{sfnp|Milne|Sethares|Plamondon|2007|p=29}}

File:Simple_I-IV-V-I_isomorphic_17-TET.mid Whereas in {{nobr|12 {{sc|EDO}},}} B{{music|natural}} is 11 steps, in {{nobr|17 {{sc|EDO}},}} B{{music|natural}} is 16 steps.]]

:

class="wikitable sortable" style="vertical-align:center;text-align:center;"
style="vertical-align:bottom;"

! interval name

! size
(steps)

! size
(cents)

! {{sc|midi}}
audio

! just
ratio

! just
(cents)

! {{sc|midi}}
audio

! error

style="text-align:center;"

| octave

| 17

| 1200 {{0}}{{0}}

|

| 2:1

| 1200 {{0}}{{0}}

|

| 0

style="text-align:center;"

| minor seventh

| 14

| 988.23

|

| 16:9

| 996.09

|

| −{{0}}7.77

style="text-align:center;background:#D4D4D4;"

| harmonic seventh

| 14

| 988.23

|

| 7:4

| 968.83

|

| +19.41

style="text-align:center;"

| perfect fifth

| 10

| 705.88

| 120px

| 3:2

| 701.96

| 120px

| +{{0}}3.93

style="text-align:center;background:#D4D4D4;"

| septimal tritone

| {{0}}8

| 564.71

| 120px

| 7:5

| 582.51

| 120px

| −17.81

style="text-align:center;"

| tridecimal narrow tritone

| {{0}}8

| 564.71

| 120px

| 18:13

| 563.38

| 120px

| +{{0}}1.32

style="text-align:center;"

| undecimal super-fourth

| {{0}}8

| 564.71

| 120px

| 11:8{{0}}

| 551.32

| 120px

| +13.39

style="text-align:center;"

| perfect fourth

| {{0}}7

| 494.12

| 120px

| 4:3

| 498.04

| 120px

| −{{0}}3.93

style="text-align:center;"

| septimal major third

| {{0}}6

| 423.53

| 120px

| 9:7

| 435.08

| 120px

| −11.55

style="text-align:center;"

| undecimal major third

| {{0}}6

| 423.53

| 120px

| 14:11

| 417.51

| 120px

| +{{0}}6.02

style="text-align:center;background:#D4D4D4;"

| major third

| {{0}}5

| 352.94

| 120px

| 5:4

| 386.31

| 120px

| −33.37

style="text-align:center;"

| tridecimal neutral third

| {{0}}5

| 352.94

| 120px

| 16:13

| 359.47

| 120px

| −{{0}}6.53

style="text-align:center;"

| undecimal neutral third

| {{0}}5

| 352.94

| 120px

| 11:9{{0}}

| 347.41

| 120px

| +{{0}}5.53

style="text-align:center;background:#D4D4D4;"

| minor third

| {{0}}4

| 282.35

| 120px

| 6:5

| 315.64

| 120px

| −33.29

style="text-align:center;"

| tridecimal minor third

| {{0}}4

| 282.35

| 120px

| 13:11

| 289.21

| 120px

| −{{0}}6.86

style="text-align:center;"

| septimal minor third

| {{0}}4

| 282.35

| 120px

| 7:6

| 266.87

| 120px

| +15.48

style="text-align:center;background:#D4D4D4;"

| septimal whole tone

| {{0}}3

| 211.76

| 120px

| 8:7

| 231.17

| 120px

| −19.41

style="text-align:center;"

| greater whole tone

| {{0}}3

| 211.76

| 120px

| 9:8

| 203.91

| 120px

| +{{0}}7.85

style="text-align:center;background:#D4D4D4;"

| lesser whole tone

| {{0}}3

| 211.76

| 120px

| 10:9{{0}}

| 182.40

| 120px

| +29.36

style="text-align:center;"

| neutral second, lesser undecimal

| {{0}}2

| 141.18

| 120px

| 12:11

| 150.64

| 120px

| −{{0}}9.46

style="text-align:center;"

| greater tridecimal {{nobr|{{small|{{sfrac| 2 | 3 }}}}-tone}}

| {{0}}2

| 141.18

| 120px

| 13:12

| 138.57

| 120px

| +{{0}}2.60

style="text-align:center;"

| lesser tridecimal {{nobr|{{small|{{sfrac| 2 | 3 }}}}-tone}}

| {{0}}2

| 141.18

| 120px

| 14:13

| 128.30

| 120px

| +12.88

style="text-align:center;background:#D4D4D4;"

| septimal diatonic semitone

| {{0}}2

| 141.18

| 120px

| 15:14

| 119.44

| 120px

| +21.73

style="text-align:center;background:#D4D4D4;"

| diatonic semitone

| {{0}}2

| 141.18

| 120px

| 16:15

| 111.73

| 120px

| +29.45

style="text-align:center;"

| septimal chromatic semitone

| {{0}}1

| {{0}}70.59

| 120px

| 21:20

| {{0}}84.47

| 120px

| −13.88

style="text-align:center;"

| chromatic semitone

| {{0}}1

| {{0}}70.59

| 120px

| 25:24

| {{0}}70.67

| 120px

| −{{0}}0.08

=Relation to 34 EDO=

{{nobr|17 {{sc|EDO}}}} is where every other step in the {{nobr|34 equal temperament}} scale is included, and the others are not accessible. Conversely {{nobr|17 {{sc|EDO}}}} is a subset of {{nobr|34 {{sc|EDO}}.}}

References

{{reflist|25em}}

Sources

  • {{cite journal

|last1=Milne |first1=Andrew

|last2=Sethares |first2=William |author2-link=William Sethares

|last3=Plamondon |first3=James

|date=Winter 2007

|title=Isomorphic controllers and dynamic tuning: Invariant fingering over a tuning continuum

|journal=Computer Music Journal

|volume=31 |number=4 |pages=15–32

|s2cid=27906745

|doi=10.1162/comj.2007.31.4.15 |doi-access=free

|url=http://www.mitpressjournals.org/doi/pdf/10.1162/comj.2007.31.4.15

|via=mitpressjournals.org

}}