Hemipyth: Difference between revisions
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A '''hemipyth''' (or '''"hemipythagorean"''') interval is an [[interval]] in the | A '''hemipyth''' (or '''"hemipythagorean"''') interval is an [[interval]] in the <math>\sqrt{2}\,.\sqrt{3}</math> [[subgroup]] i.e. intervals that can be constructed by multiplying half-integer powers of 2 and 3. | ||
Notable hemipyth intervals include the neutral third | Notable hemipyth intervals include the neutral third <math>\sqrt{\frac{3}{2}} = \frac{\sqrt{3}}{\sqrt{2}}</math>, semioctave <math>\sqrt{2}</math>, and the semifourth <math>\sqrt{\frac{4}{3}} = \frac{2}{\sqrt{3}}</math>. | ||
Many temperaments naturally produce intervals that split ~3/2, ~2 or ~4/3 exactly in half and can thus be interpreted as neutral thirds, semioctaves or semifourths within the temperament. | Many temperaments naturally produce intervals that split ~3/2, ~2, or ~4/3 exactly in half and can thus be interpreted as neutral thirds, semioctaves, or semifourths within the temperament. | ||
== Equal temperaments == | == Equal temperaments == | ||
An important property of edos | An important property of edos > 1 is that they must by necessity include at least one of the notable hemipyth intervals: | ||
* Either the edo is even and it features at least | * Either the edo is even and it features at least <math>\sqrt{2}</math> (which is tuned "pure" when the octave is tuned pure). | ||
* Or one of the following is true: | * Or one of the following is true: | ||
** The closest approximation to 3/2 spans an even number of edosteps (leading to an approximation to | ** The closest approximation to 3/2 spans an even number of edosteps (leading to an approximation to <math>\sqrt{\frac{3}{2}}</math>) | ||
** The closest approximation to 4/3 spans an even number of edosteps (leading to an approximation to | ** The closest approximation to 4/3 spans an even number of edosteps (leading to an approximation to <math>\sqrt{\frac{4}{3}}</math>) | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ style="font-size: 105%;" | List of edo mappings with full or partial hemipyth support | |+ style="font-size: 105%;" | List of edo mappings with full or partial hemipyth support | ||
|- | |- | ||
! Edo (warts) !! Has | ! Edo (warts) !! Has <math>\sqrt{2}</math> !! Has <math>\sqrt{\frac{3}{2}}</math> !! Has <math>\sqrt{\frac{4}{3}}</math> | ||
|- | |- | ||
| 2 || yes || no || no | | 2 || yes || no || no | ||
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== Notation == | == Notation == | ||
The Pythagorean 2.3 part of hemipyth can be notated using traditional notation where octaves represent multiples of 2/1, chain of fifths denotes multiples of 3/2, the sharp sign is equal to 2187/2048 etc. | The Pythagorean (2.3) part of hemipyth can be notated using traditional notation where octaves represent multiples of 2/1, chain of fifths denotes multiples of 3/2, the sharp sign is equal to 2187/2048 etc. | ||
A prototypical 5L 2s 5|1 (Ionian) scale would be spelled C, D, E, F, G, A, B, (C). | A prototypical 5L 2s 5|1 (Ionian) scale would be spelled C, D, E, F, G, A, B, (C). | ||
Simple otonal chords can be plucked out of the harmonic segment 1:2:3:4:6:8:9:12:16:18:24:27:32:36:48:54:64:72:81:96:108:128:... e.g. 6:8:9 is a sus4 chord. | Simple otonal chords can be plucked out of the harmonic segment 1:2:3:4:6:8:9:12:16:18:24:27:32:36:48:54:64:72:81:96:108:128:... e.g. 6:8:9 is a sus4 chord. | ||
=== Neutral thirds === | === Neutral thirds === | ||
The 2. | The <math>2\,.\sqrt{\frac{3}{2}}</math> part can be notated using [[neutral chain-of-fifths notation]]. This introduces a neutral interval quality between major and minor, semisharps (a.k.a. demisharps) etc. | ||
A representative 3L 4s 4|2 (kleeth) scale would be spelled C, D, E{{demiflat2}}, F, G, A{{demiflat2}}, B{{demiflat2}}, (C) | A representative 3L 4s 4|2 (kleeth) scale would be spelled {{nowrap|C, D, E{{demiflat2}}, F, G, A{{demiflat2}}, B{{demiflat2}}, (C)}} | ||
=== Semioctaves === | === Semioctaves === | ||
In traditional notation the octave spans 7 diasteps which means that it splits into two interordinal | In traditional notation the octave spans 7 diasteps which means that it splits into two interordinal {{frac|3|1|2}} diasteps or two perfect 4.5ths ("four-and-a-halves") if we wish to remain backwards compatible with the 1-indexed traditional notation. | ||
Intervals retain their quality when the frequency ratio is multiplied by the perfect semioctave | Intervals retain their quality when the frequency ratio is multiplied by the perfect semioctave <math>\sqrt{2}</math>, e.g. {{nowrap|M6 − P4.5 {{=}} M2.5 {{=}} ({{frac|9|8}})<sup>3/2</sup>}}. | ||
Relative interordinal intervals are either called by their double i.e. M2.5 is a major semifourth due to being exactly the half of an augmented fourth (Aug4), or by simply adding the suffix "-and-a-halfth" i.e. "major second-and-a-halfth". The semisecond gets the special nickname "sesquith". | Relative interordinal intervals are either called by their double i.e. M2.5 is a major semifourth due to being exactly the half of an augmented fourth (Aug4), or by simply adding the suffix "-and-a-halfth" i.e. "major second-and-a-halfth". The semisecond gets the special nickname "sesquith". | ||
The nominals for absolute pitches are denoted using lowercase Greek nominals (uppercase often looks identical to pre-existing Latin nominals). The logic being that Latin and Greek notes differ by a multiple of | The nominals for absolute pitches are denoted using lowercase Greek nominals (uppercase often looks identical to pre-existing Latin nominals). The logic being that Latin and Greek notes differ by a multiple of <math>\sqrt{2}</math> when paired up alphabetically. The direction is determined by octaves starting from the middle C. | ||
{| class="wikitable" | {| class="wikitable" | ||
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! Nominal !! Pronuciation !! Meaning !! Ratio with middle C !! Cents | ! Nominal !! Pronuciation !! Meaning !! Ratio with middle C !! Cents | ||
|- | |- | ||
| γ || gam || C + P4.5 || | | γ || gam || C + P4.5 || <math>\sqrt{2}</math> || 600.000 | ||
|- | |- | ||
| δ || del || D + P4.5 || | | δ || del || D + P4.5 || <math>\sqrt{\frac{81}{32}}</math> || 803.910 | ||
|- | |- | ||
| ε || eps || E + P4.5 || | | ε || eps || E + P4.5 || <math>\sqrt{\frac{6561}{2048}}</math> || 1007.820 | ||
|- | |- | ||
| ζ || zet || F + P4.5 || | | ζ || zet || F + P4.5 || <math>\sqrt{\frac{32}{9}}</math> || 1098.045 | ||
|- | |- | ||
| η || eta || G - P4.5 || | | η || eta || G - P4.5 || <math>\sqrt{\frac{9}{8}}</math> || 101.955 | ||
|- | |- | ||
| α || alp || A - P4.5 || (9 | | α || alp || A - P4.5 || <math>\left(\frac{9}{8}\right)^{\frac{3}{2}}</math> || 305.865 | ||
|- | |- | ||
| β || bet || B - P4.5 || (9 | | β || bet || B - P4.5 || <math>\left(\frac{9}{8}\right)^{\frac{5}{2}}</math> || 509.775 | ||
|} | |} | ||
Where to put the greek notes on a staff is still being decided. Probably on the same lines as traditional notes but with distinct noteheads. E.g. a middle η would look like a middle C, but with an upwards pointing triangular notehead. | Where to put the greek notes on a staff is still being decided. Probably on the same lines as traditional notes but with distinct noteheads. E.g. a middle η would look like a middle C, but with an upwards pointing triangular notehead. | ||
A representative 10L 2s 10|0(2) scale would be spelled C, η, D, α, E, β, γ, G, δ, A, ε, B, (C). | A representative 10L 2s 10|0(2) scale would be spelled C, η, D, α, E, β, γ, G, δ, A, ε, B, (C). | ||
An alternative solution, although one which looses bijectivity, is to keep only the traditional nominals while having a dedicated accidental pair for | An alternative solution, although one which looses bijectivity, is to keep only the traditional nominals while having a dedicated accidental pair for <math>\sqrt{\frac{256}{243}}</math> (this was proposed by [[User:CompactStar|CompactStar]]). | ||
=== Semifourths === | === Semifourths === | ||
Luckily we don't need to introduce any more generalizations to the notation to indicate | Luckily we don't need to introduce any more generalizations to the notation to indicate <math>\sqrt{\frac{4}{3}}</math>. It's a neutral {{frac|2|1|2}} or a α{{demiflat2}} (alp semiflat) w.r.t middle C. | ||
Nicknames are still assigned to make it easier to talk about the [[5L 4s]] scale generated by √(4/3) against the octave. | |||
{| class="wikitable" | {| class="wikitable" | ||
|+ style="font-size: 105%;" | Semifourth nominals | |+ style="font-size: 105%;" | Semifourth nominals | ||
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! Nominal !! Pronunciation !! Meaning !! Ratio with middle C !! Cents | ! Nominal !! Pronunciation !! Meaning !! Ratio with middle C !! Cents | ||
|- | |- | ||
| φ || phi || α{{demiflat2}} || | | φ || phi || α{{demiflat2}} || <math>\sqrt{\frac{4}{3}}</math> || 249.022 | ||
|- | |- | ||
| χ || chi || β{{demiflat2}} || | | χ || chi || β{{demiflat2}} || <math>\sqrt{\frac{27}{16}}</math> || 452.933 | ||
|- | |- | ||
| ψ || psi || ε{{demiflat2}} || | | ψ || psi || ε{{demiflat2}} || <math>\sqrt{3}</math> || 950.978 | ||
|- | |- | ||
| ω || ome || ζ{{demisharp2}} || | | ω || ome || ζ{{demisharp2}} || <math>\sqrt{\frac{243}{64}}</math> || 1154.888 | ||
|} | |} | ||
These particular definitions were chosen so that C, D, φ, χ, F, G, A, ψ, ω, (C) becomes the 6|2 (Stellerian) mode, all notated without accidentals. | These particular definitions were chosen so that {{nowrap|C, D, φ, χ, F, G, A, ψ, ω, (C)}} becomes the 6|2 (Stellerian) mode, all notated without accidentals. | ||
=== Hemipyth === | === Hemipyth === | ||
Putting it all together we can now spell a squashed Ionian scale, 10L 4s 10|2(2): | Putting it all together we can now spell a squashed Ionian scale, 10L 4s 10|2(2): | ||
C, η, D, α{{demiflat2}}, E{{demiflat2}}, β{{demiflat2}}, F{{demisharp2}}, γ, G, δ, A{{demiflat2}}, ε{{demiflat2}}, B{{demiflat2}}, ζ{{demisharp2}}, (C) | C, η, D, α{{demiflat2}}, E{{demiflat2}}, β{{demiflat2}}, F{{demisharp2}}, γ, G, δ, A{{demiflat2}}, ε{{demiflat2}}, B{{demiflat2}}, ζ{{demisharp2}}, (C) | ||
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C, η, D, φ, E{{demiflat2}}, χ, F{{demisharp2}}, γ, G, δ, A{{demiflat2}}, ψ, B{{demiflat2}}, ω, (C) | C, η, D, φ, E{{demiflat2}}, χ, F{{demisharp2}}, γ, G, δ, A{{demiflat2}}, ψ, B{{demiflat2}}, ω, (C) | ||
The 4L 6s 4|4(2) scale (called Pacific), can be spelled like so: | The 4L 6s 4|4(2) scale (called Pacific), can be spelled like so: | ||
C, η, α{{demiflat2}}, E{{demiflat2}}, F, γ, G, A{{demiflat2}}, ε{{demiflat2}}, ζ, C | C, η, α{{demiflat2}}, E{{demiflat2}}, F, γ, G, A{{demiflat2}}, ε{{demiflat2}}, ζ, C | ||
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D, α, β{{demiflat2}}, F{{demisharp2}}, G, δ, A, B{{demiflat2}}, ζ{{demisharp2}}, η, D | D, α, β{{demiflat2}}, F{{demisharp2}}, G, δ, A, B{{demiflat2}}, ζ{{demisharp2}}, η, D | ||
Simple hemipyth chords can be plucked out of the square root of the Pythagorean segment 1: | Simple hemipyth chords can be plucked out of the square root of the Pythagorean segment <math>1:</math> <math>\sqrt{2}:</math> <math>\sqrt{3}:2:</math> <math>\sqrt{6}:</math> <math>\sqrt{8}:3:</math> <math>\sqrt{12}:4:</math> <math>\sqrt{18}:</math> <math>\sqrt{24}:</math> <math>\sqrt{27}:</math> <math>\sqrt{32}:6:</math> <math>\sqrt{48}:</math> <math>\sqrt{54}:8:</math> <math>\sqrt{72}:9:</math> <math>\sqrt{96}:</math> <math>\sqrt{108}:</math> <math>\sqrt{128}:</math> <math>\ldots</math> e.g. <math>2:\sqrt{6}:3</math> is a neutral chord where spicy tension can be added by including the semioctave for <math>2:\sqrt{6}:\sqrt{8}:3</math> with no increase in complexity as far as the generator of the subgroup is concerned. | ||
Here is a [https://xenpaper.com/#%7B58edo%7D%0A%23_5L_2s_5%7C1_(Ionian)%0A0_10_20_24_34_44_54_58_54_44_34_24_20_10_0%0A....%0A%23_3L_4s_4%7C2_(kleeth)%0A0_10_17_24_34_41_51_58_51_41_34_24_17_10_0%0A....%0A%23_10L_2s_10%7C0(2)%0A0_5_10_15_20_25_29_34_39_44_49_54_58_54_49_44_39_34_29_25_20_15_10_5_0%0A....%0A%23_5L_4s_6%7C2_(Stellerian)%0A0_10_12_22_24_34_44_46_56_58_56_46_44_34_24_22_12_10_0%0A....%0A%23_10L_4s_10%7C2(2)_(Squashed_Ionian)%0A0_5_10_12_17_22_27_29_34_39_41_46_51_56_58_56_51_46_41_39_34_29_27_22_17_12_10_5_0%0A....%0A%23_4L_6s_4%7C4(2)_(Pacific)%0A0_5_12_17_24_29_34_41_46_53_58_53_46_41_34_29_24_17_12_5_0 Xenpaper demo] of all five representative scales listed above. | Here is a [https://xenpaper.com/#%7B58edo%7D%0A%23_5L_2s_5%7C1_(Ionian)%0A0_10_20_24_34_44_54_58_54_44_34_24_20_10_0%0A....%0A%23_3L_4s_4%7C2_(kleeth)%0A0_10_17_24_34_41_51_58_51_41_34_24_17_10_0%0A....%0A%23_10L_2s_10%7C0(2)%0A0_5_10_15_20_25_29_34_39_44_49_54_58_54_49_44_39_34_29_25_20_15_10_5_0%0A....%0A%23_5L_4s_6%7C2_(Stellerian)%0A0_10_12_22_24_34_44_46_56_58_56_46_44_34_24_22_12_10_0%0A....%0A%23_10L_4s_10%7C2(2)_(Squashed_Ionian)%0A0_5_10_12_17_22_27_29_34_39_41_46_51_56_58_56_51_46_41_39_34_29_27_22_17_12_10_5_0%0A....%0A%23_4L_6s_4%7C4(2)_(Pacific)%0A0_5_12_17_24_29_34_41_46_53_58_53_46_41_34_29_24_17_12_5_0 Xenpaper demo] of all five representative scales listed above. | ||
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The semioctave is always tuned pure when the octave is tuned pure. | The semioctave is always tuned pure when the octave is tuned pure. | ||
The neutral third receives only half of the tuning damage of the fifth so it has a strong character even if the fifth isn't tuned very pure. The irrational nature of | The neutral third receives only half of the tuning damage of the fifth so it has a strong character even if the fifth isn't tuned very pure. The irrational nature of <math>\sqrt{\frac{3}{2}}</math> also makes it more tolerant of imprecise tuning. | ||
The same goes for the semifourth. A poorly tuned ~4/3 still results in a decent ~ | The same goes for the semifourth. A poorly tuned ~4/3 still results in a decent <math>~\sqrt{\frac{4}{3}}</math> (assuming it's featured in the tuning in the first place). | ||
=== Signposts === | === Signposts === | ||
Due to their low damage in supporting temperaments octave 2 | Due to their low damage in supporting temperaments, the octave ({{frac|2|1}}), semioctave <math>\left(\sqrt{2}\right)</math>, perfect fifth ({{frac|3|2}}), perfect fourth ({{frac|4|3}}), neutral third <math>\left(\sqrt{\frac{3}{2}}\right)</math>, neutral sixth <math>\left(\sqrt{\frac{8}{3}}\right)</math>, semifourth <math>\left(\sqrt{\frac{4}{3}}\right)</math>, semitwelfth <math>\left(\sqrt{3}\right)</math>, "hemitone" <math>\left(\sqrt{\frac{9}{8}}\right)</math>, and "contrahemitone" <math>\left(\sqrt{\frac{32}{9}}\right)</math> all provide good signposts for navigating around otherwise unfamiliar scales. | ||
While untempered semitones usually come as unequal pairs consisting of an augmented unison and a minor second, the "hemitone" is always exactly the geometric half of a 9/8 whole tone. The "contrahemitone" is its octave-complement. | While untempered semitones usually come as unequal pairs consisting of an augmented unison and a minor second, the "hemitone" is always exactly the geometric half of a 9/8 whole tone. The "contrahemitone" is its octave-complement. | ||
== Temperament interpretations == | == Temperament interpretations == | ||
Under [[ploidacot]] classification diploid temperaments feature ~ | Under [[ploidacot]] classification diploid temperaments feature <math>~\sqrt{2}</math>, dicot temperaments have <math>~\sqrt{\frac{3}{2}}</math> and alpha-dicot temperaments feature <math>~\sqrt{\frac{4}{3}}</math> (by virtue of having a <math>~\sqrt{3}</math>). | ||
Full hemipyth support is indicated by at least "diploid dicot". Examples include: | Full hemipyth support is indicated by at least "diploid dicot". Examples include: | ||
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|+ style="font-size: 105%;" | Higher-prime interpretations of hemipyth intervals | |+ style="font-size: 105%;" | Higher-prime interpretations of hemipyth intervals | ||
|- | |- | ||
! Temperament !! ~ | ! Temperament !! <math>~\sqrt{2}</math> !! <math>~\sqrt{\frac{3}{2}}</math> !! <math>~\sqrt{\frac{4}{3}}</math> !! contorted !! rank-2 | ||
|- | |- | ||
| [[decimal]] || ~7/5 || ~5/4 || ~7/6 || no || yes | | [[decimal]] || ~7/5 || ~5/4 || ~7/6 || no || yes | ||
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| [[sruti]] || ~45/32 || ~175/144 || ~81/70 || no || yes | | [[sruti]] || ~45/32 || ~175/144 || ~81/70 || no || yes | ||
|- | |- | ||
| [[ | | [[Subgroup temperaments#Pakkanian hemipyth|pakkanian hemipyth]] || ~17/12 || ~11/9 || ~15/13 || no || yes | ||
|- | |- | ||
| [[harry]] || ~17/12 || ~11/9 || ~15/13 || yes || yes | | [[harry]] || ~17/12 || ~11/9 || ~15/13 || yes || yes | ||
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| [[semisema]] || ~108/77 || ~11/9 || ~7/6 || no || yes | | [[semisema]] || ~108/77 || ~11/9 || ~7/6 || no || yes | ||
|- | |- | ||
| [[quadritikleismic]] || ~625/441 || ~49/40 || ~125/108 || yes || yes | |||
|- | |- | ||
| [[decoid]] || ~99/70 || ~49/40 || ~4725/4096 || yes || yes | |||
|} | |} | ||
Above contorted tunings don't have a ~ | Above contorted tunings don't have a <math>~\sqrt{2}</math> period with a <math>~\sqrt{3}</math> generator, but introduce further splits. Higher than rank-2 temperaments introduce further structure that goes beyond basic hemipyth. | ||
Some possible interpretations for ~ | Some possible interpretations for <math>~\sqrt{2}</math> are: | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ style="font-size: 105%;" | Higher-prime interpretations of | |+ style="font-size: 105%;" | Higher-prime interpretations of <math>\sqrt{2}</math> | ||
|- | |- | ||
! Temperament !! ~ | ! Temperament !! <math>~\sqrt{2}</math> !! contorted !! rank-2 | ||
|- | |- | ||
| [[jubilic]] || ~7/5 || no || yes (2.5.7) | | [[jubilic]] || ~7/5 || no || yes (2.5.7) | ||
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|} | |} | ||
Some possible interpretations for ~ | Some possible interpretations for <math>~\sqrt{3}</math> are: | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ style="font-size: 105%;" | Higher-prime interpretations of | |+ style="font-size: 105%;" | Higher-prime interpretations of <math>\sqrt{3}</math> | ||
|- | |- | ||
! Temperament !! ~ | ! Temperament !! <math>~\sqrt{3}</math> !! contorted !! rank-2 | ||
|- | |- | ||
| [[semaphore]] || ~7/4 || no || yes (2.3.7) | | [[semaphore]] || ~7/4 || no || yes (2.3.7) | ||
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{| class="wikitable" | {| class="wikitable" | ||
|+ style="font-size: 105%;" | Higher-prime interpretations of | |+ style="font-size: 105%;" | Higher-prime interpretations of <math>\sqrt{\frac{3}{2}}</math> | ||
|- | |- | ||
! Temperament !! ~ | ! Temperament !! <math>\sqrt{~\frac{3}{2}}</math> !! contorted !! rank-2 | ||
|- | |- | ||
| [[dicot]] || ~5/4 || no || yes (2.3.5) | | [[dicot]] || ~5/4 || no || yes (2.3.5) | ||
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[[File:The_Hymn_of_Pergele.mp3]] | [[File:The_Hymn_of_Pergele.mp3]] | ||
The Hymn of Pergele, a short piece in [[Hemipyth]][10] 4|4(2) (Pacific mode of [[4L 6s]]), written by [[User:2^67-1|Cole]]. | The Hymn of Pergele, a short piece in [[Hemipyth]][10] 4|4(2) (Pacific mode of [[4L 6s]]), written by [[User:2^67-1|Cole]]. | ||
[[Category:Rank 2]] | [[Category:Rank 2]] | ||
[[Category:Subgroup]] | [[Category:Subgroup]] |