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{{Infobox Interval
{{Infobox Interval
| Icon =
| Name = al-Farabi quarter tone, undecimal quarter tone, io comma, Alpharabian parachroma, Alpharabian ultraprime
| Ratio = 33/32
| Color name = 1o1, ilo unison
| Monzo = -5 1 0 0 1
| Cents = 53.27294
| Name = al-Farabi quarter tone, <br>undecimal quarter tone, <br>undecimal comma, <br>Alpharabian parachroma, <br>Alpharabian ultraprime
| Color name =
| FJS name = P1<sup>11</sup>
| Sound = jid_33_32_pluck_adu_dr220.mp3
| Sound = jid_33_32_pluck_adu_dr220.mp3
| Comma = yes
}}
}}


'''33/32''', the '''al-Farabi quarter tone'''<ref>The name goes back to Abu Nasr Al-Farabi (in Western reception also Alpharabius), see [[Wikipedia: Al-Farabi]]. </ref>, '''undecimal quarter tone''', or '''undecimal comma''', is a [[superparticular]] [[ratio]] which differs by a [[385/384|keenanisma (385/384)]], from the [[36/35|septimal quarter tone (36/35)]]. Raising a just [[4/3|perfect fourth (4/3)]] by the al-Farabi quarter-tone leads to the [[11/8|undecimal super-fourth (11/8)]]. Raising it instead by 36/35 leads to the [[48/35|septimal super-fourth (48/35)]] which approximates 11/8.  Apart from this, it is also the interval between [[32/27]] and [[11/9]], and between [[9/8]] and [[12/11]].
'''33/32''', the '''al-Farabi quarter tone'''<ref group="note">The name goes back to Abu Nasr Al-Farabi (in Western reception also Alpharabius), see [[Wikipedia: Al-Farabi]].</ref>, '''undecimal quarter tone''', or '''undecimal formal comma''', is a [[superparticular]] [[ratio]] which differs by a [[385/384|keenanisma (385/384)]], from the [[36/35|septimal quarter tone (36/35)]]. Raising a just [[4/3|perfect fourth (4/3)]] by the al-Farabi quarter-tone leads to the [[11/8|undecimal superfourth (11/8)]]. Raising it instead by 36/35 leads to the [[48/35|septimal superfourth (48/35)]] which approximates 11/8.  Apart from this, it is also the interval between [[32/27]] and [[11/9]], and between [[9/8]] and [[12/11]].


Because of its close proximity to [[28/27]], form which it differs only by [[Pentacircle comma|896/891]], one could reasonably argue that 33/32 is the undecimal counterpart to 28/27 in a way, particularly if treated as an interval in its own right.  However, despite this, 33/32 generally has properties more akin to a chromatic interval than to anything resembling a diatonic interval.  In addition, 33/32 could arguably have been used as a melodic interval in the Greek Enharmonic Genus, and if so, there are several possibilities for the resulting tetrachord. The most obvious of these possibilities would be to include 32:33:34 within the interval of a perfect fourth, in which case this ancient Greek scale can be approximated in [[22edo]] and [[24edo]], with the comma 1089/1088 being tempered out so that 33/32 and 34/33 are equated.  Another possibility, however, is that the semitone was [[16/15]], which, according to [https://en.wikipedia.org/wiki/Genus_(music) Wikipedia], is indirectly attested to in the writings of Ptolemy, and thus, if 33/32 was in fact used, it would have been paired with [[512/495]].
Because of its close proximity to [[28/27]], from which it differs only by [[Pentacircle comma|896/891]], one could reasonably argue that 33/32 is the [[undecimal]] counterpart to 28/27 in a way, particularly if treated as an interval in its own right.  However, despite this, 33/32 generally has properties more akin to a chromatic interval than to anything resembling a diatonic interval.  In addition, 33/32 could arguably have been used as a melodic interval in the Greek Enharmonic Genus, and if so, there are several possibilities for the resulting [[tetrachord]]. The most obvious of these possibilities would be to include 32:33:34 within the interval of a perfect fourth, in which case this [[ancient Greek]] scale can be approximated in [[22edo]] and [[24edo]], with the comma [[1089/1088]] being tempered out so that 33/32 and 34/33 are equated.  Another possibility, however, is that the semitone was [[16/15]], which, according to [[Wikipedia: Genus (music)|Wikipedia]], is indirectly attested to in the writings of [[Ptolemy]], and thus, if 33/32 was in fact used, it would have been paired with [[512/495]].  


The interval 33/32 is significant in [[Functional Just System]] and [[Helmholtz-Ellis notation]] as the undecimal formal comma which translates a Pythagorean interval to a nearby undecimal interval.  However, it should be noted that in some significant respects, treating 33/32 as a comma rather than as an important musical interval in its own right sells it short, and results in the failure to correctly define the properties of certain intervals. Namely, a stack of two 33/32 intervals equals [[1089/1024]], a type of chromatic semitone that has [[128/121]] as its diatonic counterpart.  Furthermore, 33/32 is one of two distinct 11-limit quartertone intervals required to add up to a whole tone, with [[4096/3993]] being the other- specifically, adding 4096/3993 to a stack of three 33/32 quartertones yields [[9/8]].  In addition to all this, 33/32 finds a special place in [[User:Aura|Aura]]'s music theory not only in terms of [[Alpharabian tuning]], but also in terms of his ideas on how [[diatonic functional harmony]] extends to the realm of microtonality, and it is from these areas of microtonal theory that 33/32 acquires the names '''Alpharabian parachroma''' and '''Alphrabian ultraprime''', names that at this point are only used in these theoretical contexts.
It should be noted that in some significant respects, treating 33/32 as a comma rather than as an important musical interval in its own right sells it short, and results in the failure to correctly define the properties of certain intervals. Namely, a stack of two 33/32 intervals equals [[1089/1024]], a type of chromatic semitone that has [[128/121]] as its diatonic counterpart.  Furthermore, 33/32 is one of two distinct 11-limit quartertone intervals required to add up to a whole tone, with [[4096/3993]] being the other&mdash;specifically, adding 4096/3993 to a stack of three 33/32 quartertones yields [[9/8]].  In addition to all this, 33/32 finds a special place in [[Alpharabian tuning]] and it is from this area of microtonal theory, among a select few others, that 33/32 acquires the names "'''Alpharabian parachroma'''" and "'''Alpharabian ultraprime'''", names that at this point are only used in said theoretical contexts. While many may be accustomed to thinking of 33/32 and [[729/704]] as "semiaugmented primes", this analysis is only completely accurate when [[243/242]] is tempered out.
 
== Temperaments ==
If treated as a comma to be tempered out in the 2.3.11 [[subgroup]], it results in the [[no-fives subgroup temperaments #Io|io]] temperament, giving rise to the name '''io comma'''. The temperament is generated by a flat fifth ([[7edo]] and [[26edo]] being good tunings) which represents both [[3/2]] and [[16/11]].
 
== Approximation ==
[[22edo]] and [[23edo]]'s step sizes are good, albeit in[[consistent]] approximations of this interval. Since equal-step tuning of 33/32 is roughly equivalent to 22.5edo, 2 steps of [[45edo]] represent the interval with great accuracy. [[46edo]] inherits mapping from 23edo and does it consistently.
 
== Notation ==
This interval is significant in [[Functional Just System]] and [[Helmholtz&ndash;Ellis notation]] as the undecimal formal comma which translates a Pythagorean interval to a nearby undecimal interval.
 
=== Ben Johnston's notation ===
In [[Ben Johnston's notation]], this interval is denoted with &uarr;, and its reciprocal as &darr;. If the base note is C, then 11/8 is represented by C&ndash;F&uarr;.
 
=== Sagittal notation ===
In the [[Sagittal]] system, this comma (possibly tempered) is represented by the sagittal {{sagittal | /|\ }} and is called the '''11 medium diesis''', or '''11M''' for short, because the simplest interval it notates is 11/1 (equiv. 11/8), as for example in C–F{{nbhsp}}{{sagittal | /|\ }}. The downward version is called '''1/11M''' or '''11M down''' and is represented by {{sagittal| \!/ }}.


== See also ==
== See also ==
* [[64/33]] – its [[octave complement]]
* [[16/11]] – its [[fifth complement]]
* [[Gallery of just intervals]]
* [[Gallery of just intervals]]
* [[32/31]]
* [[1ed33/32]] &ndash; equal multiplication of this interval
* [[:File:Ji-33-32-csound-foscil-220hz.mp3]]
* [[64/33]] &ndash; its [[octave complement]]
* [[16/11]] &ndash; its [[fifth complement]]
* [[32/31]] &ndash; the tricesimoprimal counterpart
* [[:File:Ji-33-32-csound-foscil-220hz.mp3]] &ndash; alternative sound example


== References ==
== References ==
<references />
<references group="note" />


[[Category:11-limit]]
[[Category:Interval ratio]]
[[Category:Superparticular]]
[[Category:Quartertone]]
[[Category:Quartertone]]
[[Category:Alpharabian]]
[[Category:Alpharabian]]
[[Category:Medium comma]]
[[Category:Commas named after their color name]]
[[Category:Listen]]
[[Category:Commas named after polymaths]]
[[Category:Overtone]]