3/1: Difference between revisions

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m Normalising usage of Infobox Interval
As an interval of equivalence: rework. Edt isn't the main article of 3/1 equivalence
 
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{{Infobox Interval
{{Infobox Interval
| Ratio = 3/1
| Ratio = 3/1
| Name = tritave, 3rd harmonic, perfect twelfth
| Name = 3rd harmonic, tritave, triple, perfect twelfth
| Color name = w12, wa 12th
| Color name = w12, wa 12th
| Sound = jid_3_1_pluck_adu_dr220.mp3
| Sound = jid_3_1_pluck_adu_dr220.mp3
}}
}}
The '''tritave''' (interval [[ratio]] '''3/1''') is the [[interval]] between a fundamental tone and its '''3rd harmonic'''. It is perhaps the most [[consonance|consonant]] interval after the [[octave]]. For this reason, it is used as an [[equave]] in some [[nonoctave]] systems, such as the [[Bohlen-Pierce]] scale.
The '''3rd harmonic''', '''tritave''', '''triple''', or '''perfect twelfth''' is the [[interval]] of [[frequency ratio]] '''3/1'''. It is perhaps the most [[consonant]] interval after the [[octave]], with frequency ratio 2/1. For this reason, it is used as an [[equave]] in some [[nonoctave]] systems, such as the [[Bohlen–Pierce]] scale.


The tritave is one octave above [[3/2]], the perfect fifth. Therefore, in a [[5L 2s|diatonic]] context, 3/1 is also called the '''perfect twelfth'''.
It is the second [[prime harmonic]], after [[2/1]] and before [[5/1]].
 
== Importance of prime 3 ==
The [[octave-reduced]] 3rd harmonic is the perfect fifth [[3/2]], and the [[octave complement]] of 3/2 is the perfect fourth [[4/3]]. The perfect fifth and fourth are considered essential in western music theory, and in [[12edo]], stacking them makes the [[Circle of fifths|circle of fifths/fourths]]. The perfect fifth is often used as the base for constructing chords, such as the classical major triad [[4:5:6|1–5/4–3/2]] (4:5:6). The perfect fourth can also be used as a base in chords, such as [[6:7:8|1–7/6–4/3]] (6:7:8), which deviates from traditional harmony.
 
In [[just intonation]], 3/1 is the first [[prime harmonic]] that adds [[pitch class]]es besides the unison, octave, and multiples of the octave. [[Pythagorean tuning]], also known as the [[3-limit]], is the subset of just intonation containing all intervals where the only prime factors are 2 and 3. Pythagorean tuning generates the [[pentic]] and [[diatonic]] scales, and is often used as a system for interval classification in just intonation.
 
== As an interval of equivalence ==
When used as an [[interval of equivalence]], 3/1 can be called the ''tritave''. This is very xenharmonic since it assumes tritave equivalence instead of octave equivalence, so that [[1/1]], 3/1, and [[9/1]] are considered the same pitch class. Typically tritave-equivalent systems base harmony off of only [[odd harmonic]]s, for example with the [[3:5:7]] triad as analogous to 4:5:6.
 
An example of a system that is typically treated as tritave-based is the [[Bohlen–Pierce scale]]. The [[equal temperament|equal-tempered]] version of the Bohlen–Pierce scale is [[13edt]], or 13 equal divisions of the tritave. Systems can be constructed analogously to octave-equivalent harmony, for example the 9-note [[lambda]] scale, which can be considered analogous to [[diatonic]].


== Etymology ==
== Etymology ==
The term ''tritave'' was coined by [[John Pierce]]<ref>https://www.huygens-fokker.org/bpsite/intervals.html</ref>. It was derived from the word ''octave'' by replacing the perceived prefix ''octo-'' (eight, for the eighth degree of the diatonic scale) by ''tri-'' (three, for 3/1). It should be noted, however, that the ''oct'' in ''octave'' is not a prefix, but part of the single-morpheme word derived from Latin ''octavus'' (eighth).  
The term ''tritave'' was coined by [[John Pierce]]<ref>[https://www.huygens-fokker.org/bpsite/intervals.html ''The Bohlen-Pierce Site: BP Interval Properties'']</ref>. It was derived from the word ''octave'' by replacing the perceived prefix ''octo-'' (eight, for the eighth degree of the diatonic scale) by ''tri-'' (three, for 3/1). However, the ''oct'' in ''octave'' is not a prefix, but part of the single-morpheme word derived from Latin [[Wiktionary:octavus #Latin|''octavus'']] ("eighth"). In this sense, ''tritave'' is more of a contraction of ''tri-'' and ''octave'' than anything else. As such, the term usually refers to 3/1 as an interval of equivalence; in other contexts, it is more often called the perfect twelfth (after the 12th degree of the diatonic scale).
 
''Triple'' is a proposed term which relates itself to the ancient Greek concept of [[harmonic|multiples]]. It also fixes the problem of using part of the word ''octave''.
 
Since the enneatonic {{mos scalesig|4L 5s<3/1>|link=1}} ("Lambda") scale is the BP substitute for the diatonic scale, the term ''decade''<ref>[https://www.youtube.com/watch?v=Ur6GOoSNGN0 12tone – How A Pair Of Microwave Engineers Broke Music]</ref> or ''decim''{{citation needed}} (tenth degree of the Lambda scale) has been proposed as an alternative to tritave, though ''decade'' almost always refers to ten times the frequency ([[10/1]]) in audio engineering.


== See also ==
== See also ==
* [[EDT]] (equal divisions of the tritave)
* [[EDT]] (equal divisions of the tritave/twelfth)
* [[No-twos 31-limit]] – non-octave 31-limit system containing neither 2 nor primes higher than 31
* [[3/2]] – its [[octave reduced]] form
* [[Tritave complement]] – the analogue for [[octave complement]]
* [[Twelfth complement]] – the analogue for [[octave complement]]


== References ==
== References ==
<references />
<references/>


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